mpv/libmpdemux/tvi_v4l.c

/*
  Video 4 Linux input

  (C) Alex Beregszaszi <alex@naxine.org>
  
  Some ideas are based on xawtv/libng's grab-v4l.c written by
    Gerd Knorr <kraxel@bytesex.org>

  Multithreading, a/v sync and native ALSA support by
    Jindrich Makovicka <makovick@kmlinux.fjfi.cvut.cz>

  CODE IS UNDER DEVELOPMENT, NO FEATURE REQUESTS PLEASE!
*/

#include "config.h"

#if defined(USE_TV) && defined(HAVE_TV_V4L)

#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <linux/videodev.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#ifdef HAVE_SYS_SYSINFO_H
#include <sys/sysinfo.h>
#endif

#include "mp_msg.h"
#include "../libao2/afmt.h"
#include "../libvo/img_format.h"
#include "../libvo/fastmemcpy.h"

#include "tv.h"

#include "audio_in.h"

static tvi_info_t info = {
	"Video 4 Linux input",
	"v4l",
	"Alex Beregszaszi <alex@naxine.org>",
	"under development"
};

#define PAL_WIDTH  768
#define PAL_HEIGHT 576
#define PAL_FPS    25

#define NTSC_WIDTH  640
#define NTSC_HEIGHT 480
#define NTSC_FPS    29.97

#define MAX_AUDIO_CHANNELS	10

#define VID_BUF_SIZE_IMMEDIATE 2

typedef struct {
    /* general */
    char			*video_device;
    int                         video_fd;
    struct video_capability	capability;
    struct video_channel	*channels;
    int				act_channel;
    struct video_tuner		tuner;

    /* video */
    struct video_picture	picture;
    int				format;		/* output format */
    int				width;
    int				height;
    int				bytesperline;
    int				fps;

    struct video_mbuf		mbuf;
    unsigned char               *mmap;
    struct video_mmap		*buf;
    int				nbuf;

    /* audio */
    char			*audio_device;
    audio_in_t                  audio_in;

    int				audio_id;
    struct video_audio		audio[MAX_AUDIO_CHANNELS];
    int				audio_channels[MAX_AUDIO_CHANNELS];

    /* buffering stuff */
    int                         immediate_mode;

    int                         audio_buffer_size;
    int                         aud_skew_cnt;
    unsigned char		*audio_ringbuffer;
    long long			*audio_skew_buffer;
    volatile int		audio_head;
    volatile int		audio_tail;
    volatile int		audio_cnt;
    volatile long long          audio_skew;
    volatile double             audio_skew_factor;
    volatile long long          audio_skew_measure_time;
    volatile int                audio_drop;

    int                         first;
    int                         video_buffer_size_max;
    volatile int                video_buffer_size_current;
    unsigned char		**video_ringbuffer;
    long long                   *video_timebuffer;
    volatile int		video_head;
    volatile int		video_tail;
    volatile int		video_cnt;

    volatile int                shutdown;

    pthread_t			audio_grabber_thread;
    pthread_t			video_grabber_thread;
    pthread_mutex_t             audio_starter;
    pthread_mutex_t             skew_mutex;
    pthread_mutex_t             video_buffer_mutex;

    long long                   starttime;
    double                      audio_secs_per_block;
    long long                   audio_skew_total;
    long			audio_recv_blocks_total;
    long			audio_sent_blocks_total;
    
} priv_t;

#include "tvi_def.h"

static const char *device_cap2name[] = {
    "capture", "tuner", "teletext", "overlay", "chromakey", "clipping",
    "frameram", "scales", "monochrome", "subcapture", "mpeg-decoder",
    "mpeg-encoder", "mjpeg-decoder", "mjpeg-encoder", NULL
};

static const char *device_palette2name[] = {
    "-", "grey", "hi240", "rgb16", "rgb24", "rgb32", "rgb15", "yuv422",
    "yuyv", "uyvy", "yuv420", "yuv411", "raw", "yuv422p", "yuv411p",
    "yuv420p", "yuv410p"
};
#define PALETTE(x) ((x < sizeof(device_palette2name)/sizeof(char*)) ? device_palette2name[x] : "UNKNOWN")

static const char *norm2name(int mode)
{
    switch (mode) {
    case VIDEO_MODE_PAL:
	return "pal";
    case VIDEO_MODE_SECAM:
	return "secam";
    case VIDEO_MODE_NTSC:
	return "ntsc";
    case VIDEO_MODE_AUTO:
	return "auto";
    default:
	return "unknown";
    }
};

static const char *audio_mode2name(int mode)
{
    switch (mode) {
    case VIDEO_SOUND_MONO:
	return "mono";
    case VIDEO_SOUND_STEREO:
	return "stereo";
    case VIDEO_SOUND_LANG1:
	return "language1";
    case VIDEO_SOUND_LANG2:
	return "language2";
    default:
	return "unknown";
    }
};

static void *audio_grabber(void *data);
static void *video_grabber(void *data);

static int palette2depth(int palette)
{
    switch(palette)
    {
	/* component */
	case VIDEO_PALETTE_RGB555:
	    return(15);
	case VIDEO_PALETTE_RGB565:
	    return(16);
	case VIDEO_PALETTE_RGB24:
	    return(24);
	case VIDEO_PALETTE_RGB32:
	    return(32);
	/* planar */
	case VIDEO_PALETTE_YUV411P:
	case VIDEO_PALETTE_YUV420P:
	case VIDEO_PALETTE_YUV410P:
	    return(12);
	/* packed */
	case VIDEO_PALETTE_YUV422P:
	case VIDEO_PALETTE_YUV422:
	case VIDEO_PALETTE_YUYV:
	case VIDEO_PALETTE_UYVY:
	case VIDEO_PALETTE_YUV420:
	case VIDEO_PALETTE_YUV411:
	    return(16);
    }
    return(-1);
}

static int format2palette(int format)
{
    switch(format)
    {
	case IMGFMT_BGR15:
	    return(VIDEO_PALETTE_RGB555);
	case IMGFMT_BGR16:
	    return(VIDEO_PALETTE_RGB565);
	case IMGFMT_BGR24:
	    return(VIDEO_PALETTE_RGB24);
	case IMGFMT_BGR32:
	    return(VIDEO_PALETTE_RGB32);
	case IMGFMT_YV12:
	case IMGFMT_I420:
	    return(VIDEO_PALETTE_YUV420P);
	case IMGFMT_YUY2:
	    return(VIDEO_PALETTE_YUV422);
    }
    return(-1);
}

// sets and sanitizes audio buffer/block sizes
static void setup_audio_buffer_sizes(priv_t *priv)
{
    int bytes_per_sample = priv->audio_in.bytes_per_sample;

    // make the audio buffer at least 5 seconds long
    priv->audio_buffer_size = 1 + 5*priv->audio_in.samplerate
	*priv->audio_in.channels
	*bytes_per_sample/priv->audio_in.blocksize;
    if (priv->audio_buffer_size < 256) priv->audio_buffer_size = 256;

    // make the skew buffer at least 1 second long
    priv->aud_skew_cnt = 1 + 1*priv->audio_in.samplerate
	*priv->audio_in.channels
	*bytes_per_sample/priv->audio_in.blocksize;
    if (priv->aud_skew_cnt < 16) priv->aud_skew_cnt = 16;

    mp_msg(MSGT_TV, MSGL_V, "Audio capture - buffer %d blocks of %d bytes, skew average from %d meas.\n",
	   priv->audio_buffer_size, priv->audio_in.blocksize, priv->aud_skew_cnt);
}

tvi_handle_t *tvi_init_v4l(char *device, char *adevice)
{
    tvi_handle_t *h;
    priv_t *priv;
    
    h = new_handle();
    if (!h)
	return(NULL);

    priv = h->priv;

    /* set video device name */
    if (!device)
	priv->video_device = strdup("/dev/video0");
    else
	priv->video_device = strdup(device);

    /* set video device name */
    if (!adevice)
	priv->audio_device = NULL;
    else {
	priv->audio_device = strdup(adevice);
    }
    
    /* allocation failed */
    if (!priv->video_device) {
	free_handle(h);
	return(NULL);
    }

    return(h);
}

/* retrieves info about audio channels from the BTTV */
static void init_v4l_audio(priv_t *priv)
{
    int i;
    int reqmode;

    if (!priv->capability.audios) return;

    /* audio chanlist */

    mp_msg(MSGT_TV, MSGL_V, " Audio devices: %d\n", priv->capability.audios);

    mp_msg(MSGT_TV, MSGL_V, "Video capture card reports the audio setup as follows:\n");
    for (i = 0; i < priv->capability.audios; i++)
    {
	if (i >= MAX_AUDIO_CHANNELS)
	{
	    mp_msg(MSGT_TV, MSGL_ERR, "no space for more audio channels (increase in source!) (%d > %d)\n",
		   i, MAX_AUDIO_CHANNELS);
	    i = priv->capability.audios;
	    break;
	}

	priv->audio[i].audio = i;
	if (ioctl(priv->video_fd, VIDIOCGAUDIO, &priv->audio[i]) == -1)
	{
	    mp_msg(MSGT_TV, MSGL_ERR, "ioctl get audio failed: %s\n", strerror(errno));
	    break;
	}

	/* mute all channels */
	priv->audio[i].volume = 0;
	priv->audio[i].flags |= VIDEO_AUDIO_MUTE;
	reqmode = -1;
	if (tv_param_amode >= 0) {
	    switch (tv_param_amode) {
	    case 0:
		reqmode = VIDEO_SOUND_MONO;
		break;
	    case 1:
		reqmode = VIDEO_SOUND_STEREO;
		break;
	    case 2:
		reqmode = VIDEO_SOUND_LANG1;
		break;
	    case 3:
		reqmode = VIDEO_SOUND_LANG2;
		break;
	    default:
		mp_msg(MSGT_TV, MSGL_ERR, "Unknown audio mode requested.\n");
		break;
	    }
	    if (reqmode >= 0) priv->audio[i].mode = reqmode;
	}
	ioctl(priv->video_fd, VIDIOCSAUDIO, &priv->audio[i]);
	
	// get the parameters back
	if (ioctl(priv->video_fd, VIDIOCGAUDIO, &priv->audio[i]) == -1)
	{
	    mp_msg(MSGT_TV, MSGL_ERR, "ioctl get audio failed: %s\n", strerror(errno));
	    break;
	}
	    
	switch(priv->audio[i].mode)
	{
	case VIDEO_SOUND_MONO:
	case VIDEO_SOUND_LANG1:
	case VIDEO_SOUND_LANG2:
	    priv->audio_channels[i] = 1;
	    break;
	case VIDEO_SOUND_STEREO:
	    priv->audio_channels[i] = 2;
	    break;
	default:
	    mp_msg(MSGT_TV, MSGL_ERR, "Card reports an unknown audio mode !\n");
	    mp_msg(MSGT_TV, MSGL_ERR, "Trying two channel audio. Use forcechan to override.\n");
	    priv->audio_channels[i] = 2;
	    break;
	}

	if (reqmode >= 0 && priv->audio[i].mode != reqmode) {
	    mp_msg(MSGT_TV, MSGL_ERR, "Audio mode setup warning!\n");
	    mp_msg(MSGT_TV, MSGL_ERR, "Requested mode was %s, but v4l still reports %s.\n",
		   audio_mode2name(reqmode), audio_mode2name(priv->audio[i].mode));
	    mp_msg(MSGT_TV, MSGL_ERR, "You may need \"forcechan\" option to force stereo/mono audio recording.\n");
	}

	/* display stuff */
	mp_msg(MSGT_TV, MSGL_V, "  %d: %s: ", priv->audio[i].audio,
	       priv->audio[i].name);
	if (priv->audio[i].flags & VIDEO_AUDIO_MUTABLE) {
	    mp_msg(MSGT_TV, MSGL_V, "muted=%s ",
		   (priv->audio[i].flags & VIDEO_AUDIO_MUTE) ? "yes" : "no");
	}
	mp_msg(MSGT_TV, MSGL_V, "vol=%d bass=%d treble=%d balance=%d mode=%s",
	       priv->audio[i].volume, priv->audio[i].bass, priv->audio[i].treble,
	       priv->audio[i].balance, audio_mode2name(priv->audio[i].mode));
	mp_msg(MSGT_TV, MSGL_V, " chan=%d\n", priv->audio_channels[i]);

	if (tv_param_forcechan >= 0)
	    priv->audio_channels[i] = tv_param_forcechan;

	// we'll call VIDIOCSAUDIO again when starting capture
	// let's set audio mode to requested mode again for the case
	// when VIDIOCGAUDIO just cannot report the mode correctly
	if (reqmode >= 0) priv->audio[i].mode = reqmode;
    }
}

static int init(priv_t *priv)
{
    int i;

    if (tv_param_immediate == 1)
	tv_param_noaudio = 1;
    
    priv->video_ringbuffer = NULL;
    priv->video_timebuffer = NULL;
    priv->audio_ringbuffer = NULL;
    priv->audio_skew_buffer = NULL;

    priv->video_fd = open(priv->video_device, O_RDWR);
    mp_msg(MSGT_TV, MSGL_DBG2, "Video fd: %d, %x\n", priv->video_fd,
	priv->video_device);
    if (priv->video_fd == -1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "unable to open '%s': %s\n",
	    priv->video_device, strerror(errno));
	goto err;
    }
    
    /* get capabilities (priv->capability is needed!) */
    if (ioctl(priv->video_fd, VIDIOCGCAP, &priv->capability) == -1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "ioctl get capabilites failed: %s\n", strerror(errno));
	goto err;
    }

    fcntl(priv->video_fd, F_SETFD, FD_CLOEXEC);

    mp_msg(MSGT_TV, MSGL_INFO, "Selected device: %s\n", priv->capability.name);
    mp_msg(MSGT_TV, MSGL_INFO, " Capabilites: ");
    for (i = 0; device_cap2name[i] != NULL; i++)
	if (priv->capability.type & (1 << i))
	    mp_msg(MSGT_TV, MSGL_INFO, "%s ", device_cap2name[i]);
    mp_msg(MSGT_TV, MSGL_INFO, "\n");
    mp_msg(MSGT_TV, MSGL_INFO, " Device type: %d\n", priv->capability.type);
    mp_msg(MSGT_TV, MSGL_INFO, " Supported sizes: %dx%d => %dx%d\n",
	priv->capability.minwidth, priv->capability.minheight,
	priv->capability.maxwidth, priv->capability.maxheight);
    priv->width = priv->capability.minwidth;
    priv->height = priv->capability.minheight;
    mp_msg(MSGT_TV, MSGL_INFO, " Inputs: %d\n", priv->capability.channels);

    priv->channels = (struct video_channel *)malloc(sizeof(struct video_channel)*priv->capability.channels);
    if (!priv->channels)
	goto malloc_failed;
    memset(priv->channels, 0, sizeof(struct video_channel)*priv->capability.channels);
    for (i = 0; i < priv->capability.channels; i++)
    {
	priv->channels[i].channel = i;
	if (ioctl(priv->video_fd, VIDIOCGCHAN, &priv->channels[i]) == -1)
	{
	    mp_msg(MSGT_TV, MSGL_ERR, "ioctl get channel failed: %s\n", strerror(errno));
	    break;
	}
	mp_msg(MSGT_TV, MSGL_INFO, "  %d: %s: %s%s%s%s (tuner:%d, norm:%s)\n", i,
	    priv->channels[i].name,
	    (priv->channels[i].flags & VIDEO_VC_TUNER) ? "tuner " : "",
	    (priv->channels[i].flags & VIDEO_VC_AUDIO) ? "audio " : "",
	    (priv->channels[i].flags & VIDEO_TYPE_TV) ? "tv " : "",
	    (priv->channels[i].flags & VIDEO_TYPE_CAMERA) ? "camera " : "",
	    priv->channels[i].tuners,
	    norm2name(priv->channels[i].norm));
    }
    priv->act_channel = 0;

    if (!(priv->capability.type & VID_TYPE_CAPTURE))
    {
	mp_msg(MSGT_TV, MSGL_ERR, "Only grabbing supported (for overlay use another program)\n");
	goto err;
    }
    
    /* map grab buffer */
    if (ioctl(priv->video_fd, VIDIOCGMBUF, &priv->mbuf) == -1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "ioctl get mbuf failed: %s\n", strerror(errno));
	goto err;
    }

    mp_msg(MSGT_TV, MSGL_V, "mbuf: size=%d, frames=%d\n",
	priv->mbuf.size, priv->mbuf.frames);
    priv->mmap = mmap(0, priv->mbuf.size, PROT_READ|PROT_WRITE,
		MAP_SHARED, priv->video_fd, 0);
    if (priv->mmap == (unsigned char *)-1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "Unable to map memory for buffers: %s\n", strerror(errno));
	goto err;
    }
    mp_msg(MSGT_TV, MSGL_DBG2, "our buffer: %p\n", priv->mmap);

    /* num of buffers */
    priv->nbuf = priv->mbuf.frames;
    
    /* video buffers */
    priv->buf = (struct video_mmap *)malloc(priv->nbuf * sizeof(struct video_mmap));
    if (!priv->buf)
	goto malloc_failed;
    memset(priv->buf, 0, priv->nbuf * sizeof(struct video_mmap));
    
    /* init v4l audio even when we don't capture */
    init_v4l_audio(priv);

    if (!priv->capability.audios && !tv_param_force_audio) tv_param_noaudio = 1;

    /* audio init */
    if (!tv_param_noaudio) {
	
#ifdef HAVE_ALSA9
	if (tv_param_alsa)
	    audio_in_init(&priv->audio_in, AUDIO_IN_ALSA);
	else
	    audio_in_init(&priv->audio_in, AUDIO_IN_OSS);
#else
	audio_in_init(&priv->audio_in, AUDIO_IN_OSS);
#endif

	if (priv->audio_device) {
	    audio_in_set_device(&priv->audio_in, priv->audio_device);
	}

	if (tv_param_audio_id < priv->capability.audios)
	    priv->audio_id = tv_param_audio_id;
	else
	    priv->audio_id = 0;
	audio_in_set_samplerate(&priv->audio_in, 44100);
	if (priv->capability.audios) {
	    audio_in_set_channels(&priv->audio_in, priv->audio_channels[priv->audio_id]);
	} else {
	    if (tv_param_forcechan >= 0) {
		audio_in_set_channels(&priv->audio_in, tv_param_forcechan);
	    } else {
		audio_in_set_channels(&priv->audio_in, 2);
	    }
	}
	if (audio_in_setup(&priv->audio_in) < 0) return 0;
	setup_audio_buffer_sizes(priv);
    }

    return(1);

malloc_failed:
    if (priv->channels)
	free(priv->channels);
    if (priv->buf)
	free(priv->buf);
err:
    if (priv->video_fd != -1)
	close(priv->video_fd);
    return(0);
}

static int uninit(priv_t *priv)
{
    priv->shutdown = 1;

    mp_msg(MSGT_TV, MSGL_V, "Waiting for threads to finish... ");
    if (!tv_param_noaudio) {
	pthread_join(priv->audio_grabber_thread, NULL);
	pthread_mutex_destroy(&priv->audio_starter);
	pthread_mutex_destroy(&priv->skew_mutex);
    }
    pthread_mutex_destroy(&priv->video_buffer_mutex);
    pthread_join(priv->video_grabber_thread, NULL);
    mp_msg(MSGT_TV, MSGL_V, "done\n");

    if (priv->capability.audios) {
	priv->audio[priv->audio_id].volume = 0;
	priv->audio[priv->audio_id].flags |= VIDEO_AUDIO_MUTE;
	ioctl(priv->video_fd, VIDIOCSAUDIO, &priv->audio[priv->audio_id]);
    }
    
    close(priv->video_fd);

    audio_in_uninit(&priv->audio_in);

    if (priv->video_ringbuffer) {
	int i;
	for (i = 0; i < priv->video_buffer_size_current; i++) {
	    free(priv->video_ringbuffer[i]);
	}
	free(priv->video_ringbuffer);
    }
    
    if (priv->video_timebuffer)
	free(priv->video_timebuffer);
    if (!tv_param_noaudio) {
	if (priv->audio_ringbuffer)
	    free(priv->audio_ringbuffer);
	if (priv->audio_skew_buffer)
	    free(priv->audio_skew_buffer);
    }

    return(1);
}

static int get_capture_buffer_size(priv_t *priv)
{
    int bufsize, cnt;

    if (tv_param_buffer_size >= 0) {
	bufsize = tv_param_buffer_size*1024*1024;
    } else {
#ifdef HAVE_SYS_SYSINFO_H
	struct sysinfo si;
	
	sysinfo(&si);
	if (si.totalram<2*1024*1024) {
	    bufsize = 1024*1024;
	} else {
	    bufsize = si.totalram/2;
	}
#else
	bufsize = 16*1024*1024;
#endif
    }
    
    cnt = bufsize/(priv->height*priv->bytesperline);
    if (cnt < 2) cnt = 2;
    
    return cnt;
}

static int start(priv_t *priv)
{
    int i;
    int bytes_per_sample;
    
    if (ioctl(priv->video_fd, VIDIOCGPICT, &priv->picture) == -1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "ioctl get picture failed: %s\n", strerror(errno));
	return(0);
    }

    priv->picture.palette = format2palette(priv->format);
    priv->picture.depth = palette2depth(priv->picture.palette);

    if (priv->format != IMGFMT_BGR15) {
	priv->bytesperline = priv->width * priv->picture.depth / 8;
    } else {
	priv->bytesperline = priv->width * 2;
    }

    mp_msg(MSGT_TV, MSGL_V, "Picture values:\n");
    mp_msg(MSGT_TV, MSGL_V, " Depth: %d, Palette: %s (Format: %s)\n", priv->picture.depth,
	PALETTE(priv->picture.palette), vo_format_name(priv->format));
    mp_msg(MSGT_TV, MSGL_V, " Brightness: %d, Hue: %d, Colour: %d, Contrast: %d\n",
	priv->picture.brightness, priv->picture.hue,
	priv->picture.colour, priv->picture.contrast);
    

    if (ioctl(priv->video_fd, VIDIOCSPICT, &priv->picture) == -1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "ioctl set picture failed: %s\n", strerror(errno));
	return(0);
    }

    priv->nbuf = priv->mbuf.frames;
    for (i=0; i < priv->nbuf; i++)
    {
	priv->buf[i].format = priv->picture.palette;
	priv->buf[i].frame = i;
	priv->buf[i].width = priv->width;
	priv->buf[i].height = priv->height;
	mp_msg(MSGT_TV, MSGL_DBG2, "buffer: %d => %p\n", i, &priv->buf[i]);
    } 

#if 0
    {
	struct video_play_mode pmode;
	
	pmode.mode = VID_PLAY_NORMAL;
	pmode.p1 = 1;
	pmode.p2 = 0;
	if (ioctl(priv->video_fd, VIDIOCSPLAYMODE, &pmode) == -1)
	{
	    mp_msg(MSGT_TV, MSGL_ERR, "ioctl set play mode failed: %s\n", strerror(errno));
//	    return(0);
	}
    }
#endif

#if 0
    {
	struct video_window win;

	win.x = 0;
	win.y = 0;
	win.width = priv->width;
	win.height = priv->height;
	win.chromakey = -1;
	win.flags = 0;
	//win.clipcount = 0;
	
	ioctl(priv->video_fd, VIDIOCSWIN, &win);
    }

    // initialize video capture
    if (ioctl(priv->video_fd, VIDIOCCAPTURE, &one) == -1)
    {
	mp_msg(MSGT_TV, MSGL_ERR, "FATAL: ioctl ccapture failed: %s\n", strerror(errno));
	return(0);
    }
#endif

    /* setup audio parameters */
    if (!tv_param_noaudio) {
	setup_audio_buffer_sizes(priv);
	bytes_per_sample = priv->audio_in.bytes_per_sample;
	priv->audio_skew_buffer = (long long*)malloc(sizeof(long long)*priv->aud_skew_cnt);
	if (!priv->audio_skew_buffer) {
	    mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate skew buffer: %s\n", strerror(errno));
	    return 0;
	}

	priv->audio_ringbuffer = (unsigned char*)malloc(priv->audio_in.blocksize*priv->audio_buffer_size);
	if (!priv->audio_ringbuffer) {
	    mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate audio buffer: %s\n", strerror(errno));
	    return 0;
	}

	priv->audio_secs_per_block = (double)priv->audio_in.blocksize/(priv->audio_in.samplerate
								    *priv->audio_in.channels
								    *bytes_per_sample);
	priv->audio_head = 0;
	priv->audio_tail = 0;
	priv->audio_cnt = 0;
	priv->audio_drop = 0;
	priv->audio_skew = 0;
	priv->audio_skew_total = 0;
	priv->audio_recv_blocks_total = 0;
	priv->audio_sent_blocks_total = 0;
    }

    /* setup video parameters */
    if (priv->immediate_mode) {
	priv->video_buffer_size_max = VID_BUF_SIZE_IMMEDIATE;
    } else {
	priv->video_buffer_size_max = get_capture_buffer_size(priv);
    }
    priv->video_buffer_size_current = 0;

    if (!tv_param_noaudio) {
	if (priv->video_buffer_size_max < 3.0*priv->fps*priv->audio_secs_per_block) {
	    mp_msg(MSGT_TV, MSGL_ERR, "Video buffer shorter than 3 times audio frame duration.\n"
		   "You will probably experience heavy framedrops.\n");
	}
    }

    mp_msg(MSGT_TV, MSGL_V, "Using a ring buffer for maximum %d frames, %d MB total size.\n",
	   priv->video_buffer_size_max,
	   priv->video_buffer_size_max*priv->height*priv->bytesperline/(1024*1024));

    priv->video_ringbuffer = (unsigned char**)malloc(priv->video_buffer_size_max*sizeof(unsigned char*));
    if (!priv->video_ringbuffer) {
	mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate video buffer: %s\n", strerror(errno));
	return 0;
    }
    for (i = 0; i < priv->video_buffer_size_max; i++)
	priv->video_ringbuffer[i] = NULL;
    
    priv->video_timebuffer = (long long*)malloc(sizeof(long long) * priv->video_buffer_size_max);
    if (!priv->video_timebuffer) {
	mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate time buffer: %s\n", strerror(errno));
	return 0;
    }
    priv->video_head = 0;
    priv->video_tail = 0;
    priv->video_cnt = 0;
    priv->first = 1;

    if (priv->capability.audios) {
	/* enable audio */
	if (tv_param_volume >= 0)
	    priv->audio[priv->audio_id].volume = tv_param_volume;
	if (tv_param_bass >= 0)
	    priv->audio[priv->audio_id].bass = tv_param_bass;
	if (tv_param_treble >= 0)
	    priv->audio[priv->audio_id].treble = tv_param_treble;
	if (tv_param_balance >= 0)
	    priv->audio[priv->audio_id].balance = tv_param_balance;
	priv->audio[priv->audio_id].flags &= ~VIDEO_AUDIO_MUTE;
	mp_msg(MSGT_TV, MSGL_V, "Enabling tv audio. Requested setup is:\n");
	mp_msg(MSGT_TV, MSGL_V, "id=%d vol=%d bass=%d treble=%d balance=%d mode=%s",
	       priv->audio_id,
	       priv->audio[priv->audio_id].volume, priv->audio[priv->audio_id].bass, priv->audio[priv->audio_id].treble,
	       priv->audio[priv->audio_id].balance, audio_mode2name(priv->audio[priv->audio_id].mode));
	mp_msg(MSGT_TV, MSGL_V, " chan=%d\n", priv->audio_channels[priv->audio_id]);
	ioctl(priv->video_fd, VIDIOCSAUDIO, &priv->audio[priv->audio_id]);
    }
    
    /* launch capture threads */
    priv->shutdown = 0;
    if (!tv_param_noaudio) {
	pthread_mutex_init(&priv->audio_starter, NULL);
	pthread_mutex_init(&priv->skew_mutex, NULL);
	pthread_mutex_lock(&priv->audio_starter);
	pthread_create(&priv->audio_grabber_thread, NULL, audio_grabber, priv);
    }
    pthread_mutex_init(&priv->video_buffer_mutex, NULL);
    /* we'll launch the video capture later, when a first request for a frame arrives */

    return(1);
}

static int control(priv_t *priv, int cmd, void *arg)
{
    mp_msg(MSGT_TV, MSGL_DBG2, "\ndebug: control(priv=%p, cmd=%d, arg=%p)\n",
	priv, cmd, arg);
    switch(cmd)
    {
	/* ========== GENERIC controls =========== */
	case TVI_CONTROL_IS_VIDEO:
	{
	    if (priv->capability.type & VID_TYPE_CAPTURE)
		return(TVI_CONTROL_TRUE);
	    return(TVI_CONTROL_FALSE);
	}
	case TVI_CONTROL_IS_AUDIO:
	    if (priv->channels[priv->act_channel].flags & VIDEO_VC_AUDIO)
	    {
		return(TVI_CONTROL_TRUE);
	    }
	    return(TVI_CONTROL_FALSE);
	case TVI_CONTROL_IS_TUNER:
	{
//	    if (priv->capability.type & VID_TYPE_TUNER)
	    if (priv->channels[priv->act_channel].flags & VIDEO_VC_TUNER)
		return(TVI_CONTROL_TRUE);
	    return(TVI_CONTROL_FALSE);
	}

	/* ========== VIDEO controls =========== */
	case TVI_CONTROL_VID_GET_FORMAT:
	{
	    int output_fmt = -1;

	    output_fmt = priv->format;
	    (int)*(void **)arg = output_fmt;
	    mp_msg(MSGT_TV, MSGL_V, "Output format: %s\n", vo_format_name(output_fmt));
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_VID_SET_FORMAT:
	    priv->format = (int)*(void **)arg;
	    // !HACK! v4l uses BGR format instead of RGB
	    // and we have to correct this. Fortunately,
	    // tv.c reads later the format back so we
	    // can persuade it to use what we want.
	    if (IMGFMT_IS_RGB(priv->format)) {
		priv->format &= ~IMGFMT_RGB_MASK;
		priv->format |= IMGFMT_BGR;
	    }
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_GET_PLANES:
	    (int)*(void **)arg = 1; /* FIXME, also not needed at this time */
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_GET_BITS:
	    (int)*(void **)arg = palette2depth(format2palette(priv->format));
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_GET_WIDTH:
	    (int)*(void **)arg = priv->width;
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_CHK_WIDTH:
	{
	    int req_width = (int)*(void **)arg;
	    
	    mp_msg(MSGT_TV, MSGL_V, "Requested width: %d\n", req_width);
	    if ((req_width >= priv->capability.minwidth) &&
		(req_width <= priv->capability.maxwidth))
		return(TVI_CONTROL_TRUE);
	    return(TVI_CONTROL_FALSE);
	}
	case TVI_CONTROL_VID_SET_WIDTH:
	    priv->width = (int)*(void **)arg;
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_GET_HEIGHT:
	    (int)*(void **)arg = priv->height;
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_CHK_HEIGHT:
	{
	    int req_height = (int)*(void **)arg;
	    
	    mp_msg(MSGT_TV, MSGL_V, "Requested height: %d\n", req_height);
	    if ((req_height >= priv->capability.minheight) &&
		(req_height <= priv->capability.maxheight))
		return(TVI_CONTROL_TRUE);
	    return(TVI_CONTROL_FALSE);
	}
	case TVI_CONTROL_VID_SET_HEIGHT:
	    priv->height = (int)*(void **)arg;
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_GET_PICTURE:
	    if (ioctl(priv->video_fd, VIDIOCGPICT, &priv->picture) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl get picture failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_SET_PICTURE:
	    if (ioctl(priv->video_fd, VIDIOCSPICT, &priv->picture) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl get picture failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_SET_BRIGHTNESS:
	    priv->picture.brightness = (int)*(void **)arg;
	    control(priv, TVI_CONTROL_VID_SET_PICTURE, 0);
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_SET_HUE:
	    priv->picture.hue = (int)*(void **)arg;
	    control(priv, TVI_CONTROL_VID_SET_PICTURE, 0);
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_SET_SATURATION:
	    priv->picture.colour = (int)*(void **)arg;
	    control(priv, TVI_CONTROL_VID_SET_PICTURE, 0);
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_SET_CONTRAST:
	    priv->picture.contrast = (int)*(void **)arg;
	    control(priv, TVI_CONTROL_VID_SET_PICTURE, 0);
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_VID_GET_FPS:
	    (int)*(void **)arg=priv->fps;
	    return(TVI_CONTROL_TRUE);

	/* ========== TUNER controls =========== */
	case TVI_CONTROL_TUN_GET_FREQ:
	{
	    unsigned long freq;
	    
	    if (ioctl(priv->video_fd, VIDIOCGFREQ, &freq) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl get freq failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    
	    /* tuner uses khz not mhz ! */
//	    if (priv->tuner.flags & VIDEO_TUNER_LOW)
//	        freq /= 1000;
	    (unsigned long)*(void **)arg = freq;
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_TUN_SET_FREQ:
	{
	    /* argument is in MHz ! */
	    unsigned long freq = (unsigned long)*(void **)arg;
	    
	    if (priv->capability.audios) {
		priv->audio[priv->audio_id].volume = 0;
		priv->audio[priv->audio_id].flags |= VIDEO_AUDIO_MUTE;
		ioctl(priv->video_fd, VIDIOCSAUDIO, &priv->audio[priv->audio_id]);
	    }

	    mp_msg(MSGT_TV, MSGL_V, "requested frequency: %.3f\n", (float)freq/16);
	    
	    /* tuner uses khz not mhz ! */
//	    if (priv->tuner.flags & VIDEO_TUNER_LOW)
//	        freq *= 1000;
//	    mp_msg(MSGT_TV, MSGL_V, " requesting from driver: freq=%.3f\n", (float)freq/16);
	    if (ioctl(priv->video_fd, VIDIOCSFREQ, &freq) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl set freq failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    usleep(100000); // wait to supress noise during switching

	    if (priv->capability.audios) {
		priv->audio[priv->audio_id].volume = tv_param_volume;
		priv->audio[priv->audio_id].flags &= ~VIDEO_AUDIO_MUTE;
		ioctl(priv->video_fd, VIDIOCSAUDIO, &priv->audio[priv->audio_id]);
	    }

	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_TUN_GET_TUNER:
	{
	    if (ioctl(priv->video_fd, VIDIOCGTUNER, &priv->tuner) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl get tuner failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    
	    mp_msg(MSGT_TV, MSGL_V, "Tuner (%s) range: %lu -> %lu\n", priv->tuner.name,
		priv->tuner.rangelow, priv->tuner.rangehigh);
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_TUN_SET_TUNER:
	{
	    if (ioctl(priv->video_fd, VIDIOCSTUNER, &priv->tuner) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl set tuner failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_TUN_SET_NORM:
	{
	    int req_mode = (int)*(void **)arg;

	    if ((req_mode != TV_NORM_PAL) && (req_mode != TV_NORM_NTSC) && (req_mode != TV_NORM_SECAM)
		&& (req_mode != TV_NORM_PALNC) && (req_mode != TV_NORM_PALM) && (req_mode != TV_NORM_PALN)
		&& (req_mode != TV_NORM_NTSCJP)) {
		mp_msg(MSGT_TV, MSGL_ERR, "Unknown norm!\n");
		return(TVI_CONTROL_FALSE);
	    }

	    if (priv->channels[priv->act_channel].flags & VIDEO_VC_TUNER) {
		int prev_mode;
		
		control(priv, TVI_CONTROL_TUN_GET_TUNER, 0);
		if (((req_mode == TV_NORM_PAL
		      || req_mode == TV_NORM_PALNC
		      || req_mode == TV_NORM_PALN) && !(priv->tuner.flags & VIDEO_TUNER_PAL)) ||
		    ((req_mode == TV_NORM_NTSC
		      || req_mode == TV_NORM_NTSCJP
		      || req_mode == TV_NORM_PALM) && !(priv->tuner.flags & VIDEO_TUNER_NTSC)) ||
		    ((req_mode == TV_NORM_SECAM) && !(priv->tuner.flags & VIDEO_TUNER_SECAM)))
		{
		    mp_msg(MSGT_TV, MSGL_ERR, "Tuner isn't capable to set norm!\n");
		    return(TVI_CONTROL_FALSE);
		}

		prev_mode = priv->tuner.mode;

		switch(req_mode) {
		case TV_NORM_PAL:
		case TV_NORM_PALNC:
		case TV_NORM_PALN:
		    priv->tuner.mode = VIDEO_MODE_PAL;
		    break;
		case TV_NORM_NTSC:
		case TV_NORM_NTSCJP:
		case TV_NORM_PALM:
		    priv->tuner.mode = VIDEO_MODE_NTSC;
		    break;
		case TV_NORM_SECAM:
		    priv->tuner.mode = VIDEO_MODE_SECAM;
		    break;
		}
	    
		if (control(priv, TVI_CONTROL_TUN_SET_TUNER, &priv->tuner) != TVI_CONTROL_TRUE) {
		    // norm setting failed, but maybe it's only because it's fixed
		    if (priv->tuner.mode != prev_mode) return(TVI_CONTROL_FALSE); // no it really failed
		}

	    }

	    switch(req_mode) {
	    case TV_NORM_PAL:
		priv->channels[priv->act_channel].norm = VIDEO_MODE_PAL;
		break;
	    case TV_NORM_NTSC:
		priv->channels[priv->act_channel].norm = VIDEO_MODE_NTSC;
		break;
	    case TV_NORM_SECAM:
		priv->channels[priv->act_channel].norm = VIDEO_MODE_SECAM;
		break;
	    case TV_NORM_PALNC:
		priv->channels[priv->act_channel].norm = 3;
		break;
	    case TV_NORM_PALM:
		priv->channels[priv->act_channel].norm = 4;
		break;
	    case TV_NORM_PALN:
		priv->channels[priv->act_channel].norm = 5;
		break;
	    case TV_NORM_NTSCJP:
		priv->channels[priv->act_channel].norm = 6;
		break;
	    }
	    if (ioctl(priv->video_fd, VIDIOCSCHAN, &priv->channels[priv->act_channel]) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl set chan failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }

	    if (ioctl(priv->video_fd, VIDIOCGCAP, &priv->capability) == -1) {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl get capabilites failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }

	    if(req_mode == TV_NORM_PAL || req_mode == TV_NORM_SECAM || req_mode == TV_NORM_PALN || req_mode == TV_NORM_PALNC) {
		priv->fps = PAL_FPS;
            }

	    if(req_mode == TV_NORM_NTSC || req_mode == TV_NORM_NTSCJP || req_mode == TV_NORM_PALM) {
		priv->fps = NTSC_FPS;
            }

	    if(priv->height > priv->capability.maxheight) {
		priv->height = priv->capability.maxheight;
	    }

	    if(priv->width > priv->capability.maxwidth) {
		priv->width = priv->capability.maxwidth;
	    }
	    
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_TUN_GET_NORM:
	{
	    (int)*(void **)arg = priv->tuner.mode;

	    return(TVI_CONTROL_TRUE);
	}
	
	/* ========== AUDIO controls =========== */
	case TVI_CONTROL_AUD_GET_FORMAT:
	{
	    (int)*(void **)arg = AFMT_S16_LE;
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_AUD_GET_CHANNELS:
	{
	    (int)*(void **)arg = priv->audio_in.channels;
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_AUD_GET_SAMPLERATE:
	{
	    (int)*(void **)arg = priv->audio_in.samplerate;
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_AUD_GET_SAMPLESIZE:
	{
	    (int)*(void **)arg = priv->audio_in.bytes_per_sample;
	    return(TVI_CONTROL_TRUE);
	}
	case TVI_CONTROL_AUD_SET_SAMPLERATE:
	{
	    if (audio_in_set_samplerate(&priv->audio_in, (int)*(void **)arg) < 0) return TVI_CONTROL_FALSE;
	    setup_audio_buffer_sizes(priv);
	    return(TVI_CONTROL_TRUE);
	}
	/* ========== SPECIFIC controls =========== */
	case TVI_CONTROL_SPC_GET_INPUT:
	{
	    int req_chan = (int)*(void **)arg;
	    int i;

	    for (i = 0; i < priv->capability.channels; i++)
	    {
		if (priv->channels[i].channel == req_chan)
		    break;
	    }
	    
	    priv->act_channel = i;

	    if (ioctl(priv->video_fd, VIDIOCGCHAN, &priv->channels[i]) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl get channel failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    return(TVI_CONTROL_TRUE);
	}

	case TVI_CONTROL_SPC_SET_INPUT:
	{
	    struct video_channel chan;
	    int req_chan = (int)*(void **)arg;
	    int i;
	    
	    if (req_chan >= priv->capability.channels)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "Invalid input requested: %d, valid: 0-%d\n",
		    req_chan, priv->capability.channels - 1);
		return(TVI_CONTROL_FALSE);
	    }

	    for (i = 0; i < priv->capability.channels; i++)
	    {
		if (priv->channels[i].channel == req_chan)
		    chan = priv->channels[i];
	    }

	    if (ioctl(priv->video_fd, VIDIOCSCHAN, &chan) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "ioctl set chan failed: %s\n", strerror(errno));
		return(TVI_CONTROL_FALSE);
	    }
	    mp_msg(MSGT_TV, MSGL_INFO, "Using input '%s'\n", chan.name);

	    priv->act_channel = i;

	    /* update tuner state */
//	    if (priv->capability.type & VID_TYPE_TUNER)
	    if (priv->channels[priv->act_channel].flags & VIDEO_VC_TUNER)
		control(priv, TVI_CONTROL_TUN_GET_TUNER, 0);

	    /* update local channel list */	
	    control(priv, TVI_CONTROL_SPC_GET_INPUT, &req_chan);
	    return(TVI_CONTROL_TRUE);
	case TVI_CONTROL_IMMEDIATE:
	    priv->immediate_mode = 1;
	    return(TVI_CONTROL_TRUE);
	}
    }

    return(TVI_CONTROL_UNKNOWN);
}

// copies a video frame
// for RGB (i.e. BGR in mplayer) flips the image upside down
// for YV12 swaps the 2nd and 3rd plane
static inline void copy_frame(priv_t *priv, unsigned char *dest, unsigned char *source)
{
    int i;
    unsigned char *sptr;

    // YV12 uses VIDEO_PALETTE_YUV420P, but the planes are swapped
    if (priv->format == IMGFMT_YV12) {
	memcpy(dest, source, priv->width * priv->height);
	memcpy(dest+priv->width * priv->height*5/4, source+priv->width * priv->height, priv->width * priv->height/4);
	memcpy(dest+priv->width * priv->height, source+priv->width * priv->height*5/4, priv->width * priv->height/4);
	return;
    }

    switch (priv->picture.palette) {
    case VIDEO_PALETTE_RGB24:
    case VIDEO_PALETTE_RGB32:
    case VIDEO_PALETTE_RGB555:
    case VIDEO_PALETTE_RGB565:
	sptr = source + (priv->height-1)*priv->bytesperline;
	for (i = 0; i < priv->height; i++) {
	    memcpy(dest, sptr, priv->bytesperline);
	    dest += priv->bytesperline;
	    sptr -= priv->bytesperline;
	}
	break;
    case VIDEO_PALETTE_UYVY:
    case VIDEO_PALETTE_YUV420P:
    default:
	memcpy(dest, source, priv->bytesperline * priv->height);
    }
    
}

// maximum skew change, in frames
#define MAX_SKEW_DELTA 0.6
static void *video_grabber(void *data)
{
    priv_t *priv = (priv_t*)data;
    struct timeval curtime;
    long long skew, prev_skew, xskew, interval, prev_interval;
    int frame;
    int i;
    int first = 1;
    int framecount;

    /* start the capture process */

    for (i=0; i < priv->nbuf; i++) {
	if (ioctl(priv->video_fd, VIDIOCMCAPTURE, &priv->buf[i]) == -1)
	{
	    mp_msg(MSGT_TV, MSGL_ERR, "\nioctl mcapture failed: %s\n", strerror(errno));
	}
    }

    prev_interval = 0;
    prev_skew = 0;

    for (framecount = 0; !priv->shutdown;)
    {
	for (i = 0; i < priv->nbuf && !priv->shutdown; i++, framecount++) {

	    if (priv->immediate_mode) {
		while (priv->video_cnt == priv->video_buffer_size_max) {
		    usleep(10000);
                    if (priv->shutdown) {
                      return NULL;
                    }
		}
	    }
		
	    frame = i;

	    while (ioctl(priv->video_fd, VIDIOCSYNC, &priv->buf[frame].frame) < 0 &&
		   (errno == EAGAIN || errno == EINTR));
	    mp_dbg(MSGT_TV, MSGL_DBG3, "\npicture sync failed\n");

	    gettimeofday(&curtime, NULL);
	    if (first) {
		// this was a first frame - let's launch the audio capture thread immediately
		// before that, just initialize some variables
		priv->starttime = (long long)1e6*curtime.tv_sec + curtime.tv_usec;
		priv->audio_skew_measure_time = 0;
		pthread_mutex_unlock(&priv->audio_starter);
		// first frame must always have timestamp of zero
		xskew = 0;
		skew = 0;
		interval = 0;
		first = 0;
	    } else {
		if (!priv->immediate_mode) {
		    interval = (long long)1e6*curtime.tv_sec + curtime.tv_usec - priv->starttime;
		} else {
		    interval = (long long)1e6*framecount/priv->fps;
		}

		if (!priv->immediate_mode) {
		    if (interval - prev_interval == 0) {
			mp_msg(MSGT_TV, MSGL_V, "\nvideo capture thread: frame delta = 0\n");
		    } else if ((interval - prev_interval < (long long)0.85e6/priv->fps)
			       || (interval - prev_interval > (long long)1.15e6/priv->fps) ) {
			mp_msg(MSGT_TV, MSGL_V, "\nvideo capture thread: frame delta ~ %.1lf fps\n",
			       (double)1e6/(interval - prev_interval));
		    }
		}

		// interpolate the skew in time
		pthread_mutex_lock(&priv->skew_mutex);
		xskew = priv->audio_skew + (interval - priv->audio_skew_measure_time)*priv->audio_skew_factor;
		pthread_mutex_unlock(&priv->skew_mutex);
		// correct extreme skew changes to avoid (especially) moving backwards in time
		if (xskew - prev_skew > (interval - prev_interval)*MAX_SKEW_DELTA) {
		    skew = prev_skew + (interval - prev_interval)*MAX_SKEW_DELTA;
		} else if (xskew - prev_skew < -(interval - prev_interval)*MAX_SKEW_DELTA) {
		    skew = prev_skew - (interval - prev_interval)*MAX_SKEW_DELTA;
		} else {
		    skew = xskew;
		}
	    }

	    mp_msg(MSGT_TV, MSGL_DBG3, "\nfps = %lf, interval = %lf, a_skew = %f, corr_skew = %f\n",
		   (interval != prev_interval) ? (double)1e6/(interval - prev_interval) : -1,
		   (double)1e-6*interval, (double)1e-6*xskew, (double)1e-6*skew);
	    mp_msg(MSGT_TV, MSGL_DBG3, "vcnt = %d, acnt = %d\n", priv->video_cnt, priv->audio_cnt);

	    prev_skew = skew;
	    prev_interval = interval;
	    
	    /* allocate a new buffer, if needed */
	    pthread_mutex_lock(&priv->video_buffer_mutex);
	    if (priv->video_buffer_size_current < priv->video_buffer_size_max) {
		if (priv->video_cnt == priv->video_buffer_size_current) {
		    unsigned char *newbuf = (unsigned char*)malloc(priv->bytesperline * priv->height);
		    if (newbuf) {
			memmove(priv->video_ringbuffer+priv->video_tail+1, priv->video_ringbuffer+priv->video_tail,
			       (priv->video_buffer_size_current-priv->video_tail)*sizeof(unsigned char *));
			memmove(priv->video_timebuffer+priv->video_tail+1, priv->video_timebuffer+priv->video_tail,
			       (priv->video_buffer_size_current-priv->video_tail)*sizeof(long long));
			priv->video_ringbuffer[priv->video_tail] = newbuf;
			if ((priv->video_head >= priv->video_tail) && (priv->video_cnt > 0)) priv->video_head++;
			priv->video_buffer_size_current++;
		    }
		}
	    }
	    pthread_mutex_unlock(&priv->video_buffer_mutex);

	    if (priv->video_cnt == priv->video_buffer_size_current) {
		if (!priv->immediate_mode) {
		    mp_msg(MSGT_TV, MSGL_ERR, "\nvideo buffer full - dropping frame\n");
		}
	    } else {
		if (priv->immediate_mode) {
		    priv->video_timebuffer[priv->video_tail] = interval;
		} else {
		    // compensate for audio skew
		    // negative skew => there are more audio samples, increase interval
		    // positive skew => less samples, shorten the interval
		    priv->video_timebuffer[priv->video_tail] = interval - skew;
		}
		
		copy_frame(priv, priv->video_ringbuffer[priv->video_tail], priv->mmap+priv->mbuf.offsets[frame]);
		priv->video_tail = (priv->video_tail+1)%priv->video_buffer_size_current;
		priv->video_cnt++;
	    }

	    if (ioctl(priv->video_fd, VIDIOCMCAPTURE, &priv->buf[frame]) == -1)
	    {
		mp_msg(MSGT_TV, MSGL_ERR, "\nioctl mcapture failed: %s\n", strerror(errno));
		continue;
	    }

	}

    }
    return NULL;
}

static double grab_video_frame(priv_t *priv, char *buffer, int len)
{
    double interval;

    if (priv->first) {
	pthread_create(&priv->video_grabber_thread, NULL, video_grabber, priv);
	priv->first = 0;
    }

    while (priv->video_cnt == 0) {
	usleep(10000);
    }

    pthread_mutex_lock(&priv->video_buffer_mutex);
    interval = (double)priv->video_timebuffer[priv->video_head]*1e-6;
    memcpy(buffer, priv->video_ringbuffer[priv->video_head], len);
    priv->video_cnt--;
    priv->video_head = (priv->video_head+1)%priv->video_buffer_size_current;
    pthread_mutex_unlock(&priv->video_buffer_mutex);
    return interval;
}

static int get_video_framesize(priv_t *priv)
{
    return(priv->bytesperline * priv->height);
}

static void *audio_grabber(void *data)
{
    priv_t *priv = (priv_t*)data;
    struct timeval tv;
    int i, audio_skew_ptr = 0;
    long long current_time, prev_skew = 0;

    pthread_mutex_lock(&priv->audio_starter);

    audio_in_start_capture(&priv->audio_in);
    for (i = 0; i < priv->aud_skew_cnt; i++)
	priv->audio_skew_buffer[i] = 0;

    for (; !priv->shutdown;)
    {
	if (audio_in_read_chunk(&priv->audio_in, priv->audio_ringbuffer+priv->audio_tail*priv->audio_in.blocksize) < 0)
	    continue;

	gettimeofday(&tv, NULL);

	priv->audio_recv_blocks_total++;
	current_time = (long long)1e6*tv.tv_sec + tv.tv_usec - priv->starttime;

	priv->audio_skew_total -= priv->audio_skew_buffer[audio_skew_ptr];
	priv->audio_skew_buffer[audio_skew_ptr] = current_time
	    - 1e6*priv->audio_secs_per_block*priv->audio_recv_blocks_total;
	priv->audio_skew_total += priv->audio_skew_buffer[audio_skew_ptr];
	audio_skew_ptr = (audio_skew_ptr+1) % priv->aud_skew_cnt;

	pthread_mutex_lock(&priv->skew_mutex);
	// linear interpolation - here we interpolate current skew value
	// from the moving average, which we expect to be in the middle
	// of the interval
	if (priv->audio_recv_blocks_total > priv->aud_skew_cnt) {
	    priv->audio_skew = priv->audio_skew_total/priv->aud_skew_cnt;
	    priv->audio_skew += (priv->audio_skew*priv->aud_skew_cnt)/(2*priv->audio_recv_blocks_total-priv->aud_skew_cnt);
	} else {
	    // this smoothes the evolution of audio_skew at startup a bit
	    priv->audio_skew = ((priv->aud_skew_cnt+priv->audio_recv_blocks_total)*priv->audio_skew_total)/(priv->aud_skew_cnt*priv->audio_recv_blocks_total);
	}
	// current skew factor (assuming linearity)
	// used for further interpolation in video_grabber
	// probably overkill but seems to be necessary for
	// stress testing by dropping half of the audio frames ;)
	// especially when using ALSA with large block sizes
	// where audio_skew remains a long while behind
	if ((priv->audio_skew_measure_time != 0) && (current_time - priv->audio_skew_measure_time != 0)) {
	    priv->audio_skew_factor = (double)(priv->audio_skew-prev_skew)/(current_time - priv->audio_skew_measure_time);
	} else {
	    priv->audio_skew_factor = 0.0;
	}
	
	priv->audio_skew_measure_time = current_time;
	prev_skew = priv->audio_skew;
	pthread_mutex_unlock(&priv->skew_mutex);
	
	if ((priv->audio_tail+1) % priv->audio_buffer_size == priv->audio_head) {
	    mp_msg(MSGT_TV, MSGL_ERR, "\ntoo bad - dropping audio frame !\n");
	    priv->audio_drop++;
	} else {
	    priv->audio_tail = (priv->audio_tail+1) % priv->audio_buffer_size;
	    priv->audio_cnt++;
	}
    }
    return NULL;
}

static double grab_audio_frame(priv_t *priv, char *buffer, int len)
{
    mp_dbg(MSGT_TV, MSGL_DBG2, "grab_audio_frame(priv=%p, buffer=%p, len=%d)\n",
	priv, buffer, len);

    // compensate for dropped audio frames
    if (priv->audio_drop && (priv->audio_head == priv->audio_tail)) {
	priv->audio_drop--;
	priv->audio_sent_blocks_total++;
	memset(buffer, 0, len);
	return (double)priv->audio_sent_blocks_total*priv->audio_secs_per_block;
    }

    while (priv->audio_head == priv->audio_tail) {
	usleep(10000);
    }
    memcpy(buffer, priv->audio_ringbuffer+priv->audio_head*priv->audio_in.blocksize, len);
    priv->audio_head = (priv->audio_head+1) % priv->audio_buffer_size;
    priv->audio_cnt--;
    priv->audio_sent_blocks_total++;
    return (double)priv->audio_sent_blocks_total*priv->audio_secs_per_block;
}

static int get_audio_framesize(priv_t *priv)
{
    return(priv->audio_in.blocksize);
}

#endif /* USE_TV */