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avformat/imf: add support for input seeking

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The IMF demuxer did not implement AVInputFormat::read_seek2(), resulting in
inefficient input seeking.

Addresses https://trac.ffmpeg.org/ticket/9648

Byte- and frame-seeking are not supported.

Signed-off-by: Zane van Iperen <zane@zanevaniperen.com>
release/5.1
Pierre-Anthony Lemieux 3 years ago committed by Zane van Iperen
parent 9ca4d80d6b
commit 32b9f5ac2f
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GPG Key ID: 68616B2D8AC4DCC5
1 changed files with 102 additions and 27 deletions
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  1. 129
      libavformat/imfdec.c

129
libavformat/imfdec.c
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@ -359,13 +359,15 @@ static IMFAssetLocator *find_asset_map_locator(IMFAssetLocatorMap *asset_map, FF
}
static int open_track_resource_context(AVFormatContext *s,
IMFVirtualTrackResourcePlaybackCtx *track_resource)
IMFVirtualTrackPlaybackCtx *track,
int32_t resource_index)
{
IMFContext *c = s->priv_data;
int ret = 0;
int64_t entry_point;
int64_t seek_offset = 0;
AVDictionary *opts = NULL;
AVStream *st;
IMFVirtualTrackResourcePlaybackCtx *track_resource = track->resources + resource_index;
if (track_resource->ctx) {
av_log(s,
@ -416,32 +418,27 @@ static int open_track_resource_context(AVFormatContext *s,
st = track_resource->ctx->streams[0];
/* Warn if the resource time base does not match the file time base */
if (av_cmp_q(st->time_base, av_inv_q(track_resource->resource->base.edit_rate)))
av_log(s,
AV_LOG_WARNING,
"Incoherent source stream timebase " AVRATIONAL_FORMAT
"regarding resource edit rate: " AVRATIONAL_FORMAT,
st->time_base.num,
st->time_base.den,
track_resource->resource->base.edit_rate.den,
track_resource->resource->base.edit_rate.num);
entry_point = av_rescale_q(track_resource->resource->base.entry_point, st->time_base,
av_inv_q(track_resource->resource->base.edit_rate));
if (entry_point) {
av_log(s,
AV_LOG_DEBUG,
"Seek at resource %s entry point: %" PRIu32 "\n",
track_resource->locator->absolute_uri,
track_resource->resource->base.entry_point);
ret = avformat_seek_file(track_resource->ctx, 0, entry_point, entry_point, entry_point, 0);
/* Determine the seek offset into the Track File, taking into account:
* - the current timestamp within the virtual track
* - the entry point of the resource
*/
if (imf_time_to_ts(&seek_offset,
av_sub_q(track->current_timestamp, track_resource->ts_offset),
st->time_base))
av_log(s, AV_LOG_WARNING, "Incoherent stream timebase " AVRATIONAL_FORMAT
"and composition timeline position: " AVRATIONAL_FORMAT "\n",
st->time_base.num, st->time_base.den,
track->current_timestamp.den, track->current_timestamp.num);
if (seek_offset) {
av_log(s, AV_LOG_DEBUG, "Seek at resource %s entry point: %" PRIi64 "\n",
track_resource->locator->absolute_uri, seek_offset);
ret = avformat_seek_file(track_resource->ctx, 0, seek_offset, seek_offset, seek_offset, 0);
if (ret < 0) {
av_log(s,
AV_LOG_ERROR,
"Could not seek at %" PRId64 "on %s: %s\n",
entry_point,
seek_offset,
track_resource->locator->absolute_uri,
av_err2str(ret));
avformat_close_input(&track_resource->ctx);
@ -584,7 +581,7 @@ static int set_context_streams_from_tracks(AVFormatContext *s)
AVStream *first_resource_stream;
/* Open the first resource of the track to get stream information */
ret = open_track_resource_context(s, &c->tracks[i]->resources[0]);
ret = open_track_resource_context(s, c->tracks[i], 0);
if (ret)
return ret;
first_resource_stream = c->tracks[i]->resources[0].ctx->streams[0];
@ -774,7 +771,7 @@ static int get_resource_context_for_timestamp(AVFormatContext *s, IMFVirtualTrac
"Switch resource on track %d: re-open context\n",
track->index);
ret = open_track_resource_context(s, track->resources + i);
ret = open_track_resource_context(s, track, i);
if (ret != 0)
return ret;
if (track->current_resource_index > 0)
@ -942,6 +939,83 @@ static int imf_probe(const AVProbeData *p)
return AVPROBE_SCORE_MAX;
}
static void rescale_interval(AVRational tb_in, AVRational tb_out,
int64_t *min_ts, int64_t *ts, int64_t *max_ts)
{
*ts = av_rescale_q(*ts, tb_in, tb_out);
*min_ts = av_rescale_q_rnd(*min_ts, tb_in, tb_out, AV_ROUND_UP | AV_ROUND_PASS_MINMAX);
*max_ts = av_rescale_q_rnd(*max_ts, tb_in, tb_out, AV_ROUND_DOWN | AV_ROUND_PASS_MINMAX);
}
static int coherent_ts(int64_t ts, AVRational in_tb, AVRational out_tb)
{
int dst_num;
int dst_den;
int ret;
ret = av_reduce(&dst_num, &dst_den, ts * in_tb.num * out_tb.den,
in_tb.den * out_tb.num, INT64_MAX);
if (!ret || dst_den != 1)
return 0;
return 1;
}
static int imf_seek(AVFormatContext *s, int stream_index, int64_t min_ts,
int64_t ts, int64_t max_ts, int flags)
{
IMFContext *c = s->priv_data;
uint32_t i;
if (flags & (AVSEEK_FLAG_BYTE | AVSEEK_FLAG_FRAME))
return AVERROR(ENOSYS);
/* rescale timestamps to Composition edit units */
if (stream_index < 0)
rescale_interval(AV_TIME_BASE_Q,
av_make_q(c->cpl->edit_rate.den, c->cpl->edit_rate.num),
&min_ts, &ts, &max_ts);
else
rescale_interval(s->streams[stream_index]->time_base,
av_make_q(c->cpl->edit_rate.den, c->cpl->edit_rate.num),
&min_ts, &ts, &max_ts);
/* requested timestamp bounds are too close */
if (max_ts < min_ts)
return -1;
/* clamp requested timestamp to provided bounds */
ts = FFMAX(FFMIN(ts, max_ts), min_ts);
av_log(s, AV_LOG_DEBUG, "Seeking to Composition Playlist edit unit %" PRIi64 "\n", ts);
/* set the dts of each stream and temporal offset of each track */
for (i = 0; i < c->track_count; i++) {
AVStream *st = s->streams[i];
IMFVirtualTrackPlaybackCtx *t = c->tracks[i];
int64_t dts;
if (!coherent_ts(ts, av_make_q(c->cpl->edit_rate.den, c->cpl->edit_rate.num),
st->time_base))
av_log(s, AV_LOG_WARNING, "Seek position is not coherent across tracks\n");
dts = av_rescale(ts,
st->time_base.den * c->cpl->edit_rate.den,
st->time_base.num * c->cpl->edit_rate.num);
av_log(s, AV_LOG_DEBUG, "Seeking to dts=%" PRId64 " on stream_index=%d\n",
dts, i);
t->current_timestamp = av_mul_q(av_make_q(dts, 1), st->time_base);
if (t->current_resource_index >= 0) {
avformat_close_input(&t->resources[t->current_resource_index].ctx);
t->current_resource_index = -1;
}
}
return 0;
}
static const AVOption imf_options[] = {
{
.name = "assetmaps",
@ -966,7 +1040,7 @@ static const AVClass imf_class = {
const AVInputFormat ff_imf_demuxer = {
.name = "imf",
.long_name = NULL_IF_CONFIG_SMALL("IMF (Interoperable Master Format)"),
.flags = AVFMT_EXPERIMENTAL,
.flags = AVFMT_EXPERIMENTAL | AVFMT_NO_BYTE_SEEK,
.flags_internal = FF_FMT_INIT_CLEANUP,
.priv_class = &imf_class,
.priv_data_size = sizeof(IMFContext),
@ -974,4 +1048,5 @@ const AVInputFormat ff_imf_demuxer = {
.read_header = imf_read_header,
.read_packet = imf_read_packet,
.read_close = imf_close,
.read_seek2 = imf_seek,
};

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