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ffmpeg/libavformat/rtpdec_vp8.c

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/*
* RTP VP8 Depacketizer
* Copyright (c) 2010 Josh Allmann
* Copyright (c) 2012 Martin Storsjo
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* @brief RTP support for the VP8 payload
* @author Josh Allmann <joshua.allmann@gmail.com>
* @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05
*/
#include "libavutil/intreadwrite.h"
#include "avio_internal.h"
#include "rtpdec.h"
struct PayloadContext {
AVIOContext *data;
uint32_t timestamp;
int is_keyframe;
/* If sequence_ok is set, we keep returning data (even if we might have
* lost some data, but we haven't lost any too critical data that would
* cause the decoder to desynchronize and output random garbage).
*/
int sequence_ok;
int first_part_size;
uint16_t prev_seq;
int prev_pictureid;
int broken_frame;
/* If sequence_dirty is set, we have lost some data (critical or
* non-critical) and decoding will have some sort of artifacts, and
* we thus should request a new keyframe.
*/
int sequence_dirty;
int got_keyframe;
};
static int vp8_broken_sequence(AVFormatContext *ctx, PayloadContext *vp8,
const char *msg)
{
vp8->sequence_ok = 0;
av_log(ctx, AV_LOG_WARNING, "%s", msg);
ffio_free_dyn_buf(&vp8->data);
return AVERROR(EAGAIN);
}
static int vp8_handle_packet(AVFormatContext *ctx, PayloadContext *vp8,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, uint16_t seq,
int flags)
{
int start_partition, end_packet;
int extended_bits, part_id;
int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0,
keyidx_present = 0;
int pictureid = -1, pictureid_mask = 0;
int returned_old_frame = 0;
uint32_t old_timestamp = 0;
if (!buf) {
if (vp8->data) {
int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
if (ret < 0)
return ret;
*timestamp = vp8->timestamp;
if (vp8->sequence_dirty)
pkt->flags |= AV_PKT_FLAG_CORRUPT;
return 0;
}
return AVERROR(EAGAIN);
}
if (len < 1)
return AVERROR_INVALIDDATA;
extended_bits = buf[0] & 0x80;
start_partition = buf[0] & 0x10;
part_id = buf[0] & 0x0f;
end_packet = flags & RTP_FLAG_MARKER;
buf++;
len--;
if (extended_bits) {
if (len < 1)
return AVERROR_INVALIDDATA;
pictureid_present = buf[0] & 0x80;
tl0picidx_present = buf[0] & 0x40;
tid_present = buf[0] & 0x20;
keyidx_present = buf[0] & 0x10;
buf++;
len--;
}
if (pictureid_present) {
if (len < 1)
return AVERROR_INVALIDDATA;
if (buf[0] & 0x80) {
if (len < 2)
return AVERROR_INVALIDDATA;
pictureid = AV_RB16(buf) & 0x7fff;
pictureid_mask = 0x7fff;
buf += 2;
len -= 2;
} else {
pictureid = buf[0] & 0x7f;
pictureid_mask = 0x7f;
buf++;
len--;
}
}
if (tl0picidx_present) {
// Ignoring temporal level zero index
buf++;
len--;
}
if (tid_present || keyidx_present) {
// Ignoring temporal layer index, layer sync bit and keyframe index
buf++;
len--;
}
if (len < 1)
return AVERROR_INVALIDDATA;
if (start_partition && part_id == 0 && len >= 3) {
int res;
int non_key = buf[0] & 0x01;
if (!non_key) {
ffio_free_dyn_buf(&vp8->data);
// Keyframe, decoding ok again
vp8->sequence_ok = 1;
vp8->sequence_dirty = 0;
vp8->got_keyframe = 1;
} else {
int can_continue = vp8->data && !vp8->is_keyframe &&
avio_tell(vp8->data) >= vp8->first_part_size;
if (!vp8->sequence_ok)
return AVERROR(EAGAIN);
if (!vp8->got_keyframe)
return vp8_broken_sequence(ctx, vp8, "Keyframe missing\n");
if (pictureid >= 0) {
if (pictureid != ((vp8->prev_pictureid + 1) & pictureid_mask)) {
return vp8_broken_sequence(ctx, vp8,
"Missed a picture, sequence broken\n");
} else {
if (vp8->data && !can_continue)
return vp8_broken_sequence(ctx, vp8,
"Missed a picture, sequence broken\n");
}
} else {
uint16_t expected_seq = vp8->prev_seq + 1;
int16_t diff = seq - expected_seq;
if (vp8->data) {
// No picture id, so we can't know if missed packets
// contained any new frames. If diff == 0, we did get
// later packets from the same frame (matching timestamp),
// so we know we didn't miss any frame. If diff == 1 and
// we still have data (not flushed by the end of frame
// marker), the single missed packet must have been part
// of the same frame.
if ((diff == 0 || diff == 1) && can_continue) {
// Proceed with what we have
} else {
return vp8_broken_sequence(ctx, vp8,
"Missed too much, sequence broken\n");
}
} else {
if (diff != 0)
return vp8_broken_sequence(ctx, vp8,
"Missed unknown data, sequence broken\n");
}
}
if (vp8->data) {
vp8->sequence_dirty = 1;
if (avio_tell(vp8->data) >= vp8->first_part_size) {
int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
if (ret < 0)
return ret;
pkt->flags |= AV_PKT_FLAG_CORRUPT;
returned_old_frame = 1;
old_timestamp = vp8->timestamp;
} else {
// Shouldn't happen
ffio_free_dyn_buf(&vp8->data);
}
}
}
vp8->first_part_size = (AV_RL16(&buf[1]) << 3 | buf[0] >> 5) + 3;
if ((res = avio_open_dyn_buf(&vp8->data)) < 0)
return res;
vp8->timestamp = *timestamp;
vp8->broken_frame = 0;
vp8->prev_pictureid = pictureid;
vp8->is_keyframe = !non_key;
} else {
uint16_t expected_seq = vp8->prev_seq + 1;
if (!vp8->sequence_ok)
return AVERROR(EAGAIN);
if (vp8->timestamp != *timestamp) {
// Missed the start of the new frame, sequence broken
return vp8_broken_sequence(ctx, vp8,
"Received no start marker; dropping frame\n");
}
if (seq != expected_seq) {
if (vp8->is_keyframe) {
return vp8_broken_sequence(ctx, vp8,
"Missed part of a keyframe, sequence broken\n");
} else if (vp8->data && avio_tell(vp8->data) >= vp8->first_part_size) {
vp8->broken_frame = 1;
vp8->sequence_dirty = 1;
} else {
return vp8_broken_sequence(ctx, vp8,
"Missed part of the first partition, sequence broken\n");
}
}
}
if (!vp8->data)
return vp8_broken_sequence(ctx, vp8, "Received no start marker\n");
vp8->prev_seq = seq;
if (!vp8->broken_frame)
avio_write(vp8->data, buf, len);
if (returned_old_frame) {
*timestamp = old_timestamp;
return end_packet ? 1 : 0;
}
if (end_packet) {
int ret;
ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
if (ret < 0)
return ret;
if (vp8->sequence_dirty)
pkt->flags |= AV_PKT_FLAG_CORRUPT;
if (vp8->is_keyframe)
pkt->flags |= AV_PKT_FLAG_KEY;
return 0;
}
return AVERROR(EAGAIN);
}
static av_cold int vp8_init(AVFormatContext *s, int st_index, PayloadContext *vp8)
{
vp8->sequence_ok = 1;
return 0;
}
static void vp8_close_context(PayloadContext *vp8)
{
ffio_free_dyn_buf(&vp8->data);
}
static int vp8_need_keyframe(PayloadContext *vp8)
{
return vp8->sequence_dirty || !vp8->sequence_ok;
}
const RTPDynamicProtocolHandler ff_vp8_dynamic_handler = {
.enc_name = "VP8",
.codec_type = AVMEDIA_TYPE_VIDEO,
.codec_id = AV_CODEC_ID_VP8,
.priv_data_size = sizeof(PayloadContext),
.init = vp8_init,
.close = vp8_close_context,
.parse_packet = vp8_handle_packet,
.need_keyframe = vp8_need_keyframe,
};
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