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demux_lavf: minimal probing and reduced analyzeduration for AAC over HTTP 

When AAC is streamed over HTTP, using libavformat defaults is
pathetically slow. One solution for that is skipping probing and using
the mimetype to identify that it's AAC instead. This is what we did
before this commit (and ffmpeg does it too, but their logic is too
"inaccessible" for mpv).

This is still pretty fragile though. Make it a bit more robust by
requiring minimal probing. A probescore of 25 is reached after feeding
2 KB to libavformat (instead of > 500 KB for the normal probescore), so
use that. This is done only when streaming AAC from HTTP to reduce the
possibility of weird breakages for other formats.

Also reduce analyzeduration. The default analyzeduration will make
libavformat read lots of data, which makes playback start slow. So we
set analyzeduration to a low value. On the other hand, doing that for
other formats is risky, because there are unspecified effects with
certain "strange" formats (like transport streams). So we do this only
if we're streaming AAC from HTTP as well.

tl;dr libavformat is shit for media players
This commit is contained in:
wm4 2013-05-27 23:26:22 +02:00
parent f05ec1c738
commit 8cfb87d200
2 changed files with 44 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
core/options.h
View File

@ -222,7 +222,7 @@ typedef struct MPOpts {
struct lavfdopts {
int probesize;
int probescore;
int analyzeduration;
float analyzeduration;
int allow_mimetype;
char *format;
char *cryptokey;

57
demux/demux_lavf.c
View File

@ -54,7 +54,7 @@
const m_option_t lavfdopts_conf[] = {
OPT_INTRANGE("probesize", lavfdopts.probesize, 0, 32, INT_MAX),
OPT_STRING("format", lavfdopts.format, 0),
OPT_INTRANGE("analyzeduration", lavfdopts.analyzeduration, 0, 0, INT_MAX),
OPT_FLOATRANGE("analyzeduration", lavfdopts.analyzeduration, 0, 0, 3600),
OPT_FLAG("allow-mimetype", lavfdopts.allow_mimetype, 0),
OPT_INTRANGE("probescore", lavfdopts.probescore, 0, 0, 100),
OPT_STRING("cryptokey", lavfdopts.cryptokey, 0),
@ -68,6 +68,7 @@ const m_option_t lavfdopts_conf[] = {
typedef struct lavf_priv {
char *filename;
const struct format_hack *format_hack;
AVInputFormat *avif;
AVFormatContext *avfc;
AVIOContext *pb;
@ -83,16 +84,23 @@ typedef struct lavf_priv {
char *mime_type;
} lavf_priv_t;
static const char *map_demuxer_mime_type[][2] = {
{"audio/aacp", "aac"},
struct format_hack {
const char *ff_name;
const char *mime_type;
int probescore;
float analyzeduration;
};
static const struct format_hack format_hacks[] = {
{"aac", "audio/aacp", 25, 0.5},
{0}
};
static const char *find_demuxer_from_mime_type(char *mime_type)
static const struct format_hack *find_format_from_mime_type(char *mime_type)
{
for (int n = 0; map_demuxer_mime_type[n][0]; n++) {
if (strcasecmp(map_demuxer_mime_type[n][0], mime_type) == 0)
return map_demuxer_mime_type[n][1];
for (int n = 0; format_hacks[n].ff_name; n++) {
if (strcasecmp(format_hacks[n].mime_type, mime_type) == 0)
return &format_hacks[n];
}
return NULL;
}
@ -214,13 +222,23 @@ static int lavf_check_file(demuxer_t *demuxer)
priv->filename = sep + 1;
}
char *format = lavfdopts->format;
const char *expected_format = NULL;
int expected_format_probescore = AVPROBE_SCORE_MAX;
char *mime_type = demuxer->stream->mime_type;
if (lavfdopts->allow_mimetype && mime_type) {
priv->format_hack = find_format_from_mime_type(mime_type);
if (priv->format_hack) {
expected_format = priv->format_hack->ff_name;
expected_format_probescore = priv->format_hack->probescore;
}
}
const char *format = lavfdopts->format;
if (!format)
format = demuxer->stream->lavf_type;
if (!format)
format = avdevice_format;
if (!format && lavfdopts->allow_mimetype && demuxer->stream->mime_type)
format = (char *)find_demuxer_from_mime_type(demuxer->stream->mime_type);
if (format) {
if (strcmp(format, "help") == 0) {
list_formats();
@ -265,7 +283,12 @@ static int lavf_check_file(demuxer_t *demuxer)
}
if (priv->avif && score >= min_probe)
break;
break;
if (priv->avif && expected_format) {
if (strcmp(priv->avif->name, expected_format) == 0 &&
score >= expected_format_probescore)
break;
}
priv->avif = NULL;
read_size = FFMIN(2 * read_size, PROBE_BUF_SIZE - probe_data_size);
@ -457,6 +480,7 @@ static demuxer_t *demux_open_lavf(demuxer_t *demuxer)
AVFormatContext *avfc;
AVDictionaryEntry *t = NULL;
lavf_priv_t *priv = demuxer->priv;
float analyze_duration = 0;
int i;
// do not allow forcing the demuxer
@ -487,11 +511,16 @@ static demuxer_t *demux_open_lavf(demuxer_t *demuxer)
"demux_lavf, couldn't set option probesize to %u\n",
lavfdopts->probesize);
}
if (lavfdopts->analyzeduration) {
if (priv->format_hack && priv->format_hack->analyzeduration)
analyze_duration = priv->format_hack->analyzeduration;
if (lavfdopts->analyzeduration)
analyze_duration = lavfdopts->analyzeduration;
if (analyze_duration > 0) {
if (av_opt_set_int(avfc, "analyzeduration",
lavfdopts->analyzeduration * AV_TIME_BASE, 0) < 0)
analyze_duration * AV_TIME_BASE, 0) < 0)
mp_msg(MSGT_HEADER, MSGL_ERR, "demux_lavf, couldn't set option "
"analyzeduration to %u\n", lavfdopts->analyzeduration);
"analyzeduration to %f\n", analyze_duration);
}
if (lavfdopts->avopt) {