[FFmpeg-devel] [PATCH v1 3/4] avformat/imf: fix packet pts, dts and muxing
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Mon Jan 31 00:16:17 EET 2022
pal at sandflow.com:
> From: Pierre-Anthony Lemieux <pal at palemieux.com>
>
> The IMF demuxer does not set the DTS and PTS of packets accurately in all
> scenarios. Moreover, audio packets are not trimmed when they exceed the
> duration of the underlying resource.
>
> Closes https://trac.ffmpeg.org/ticket/9611
>
> ---
> libavformat/imfdec.c | 225 +++++++++++++++++++++++++------------------
> 1 file changed, 132 insertions(+), 93 deletions(-)
>
> diff --git a/libavformat/imfdec.c b/libavformat/imfdec.c
> index 6b50b582f6..05dcb6ff31 100644
> --- a/libavformat/imfdec.c
> +++ b/libavformat/imfdec.c
> @@ -65,6 +65,7 @@
> #include "avio_internal.h"
> #include "imf.h"
> #include "internal.h"
> +#include "libavcodec/packet.h"
> #include "libavutil/avstring.h"
> #include "libavutil/bprint.h"
> #include "libavutil/opt.h"
> @@ -97,6 +98,9 @@ typedef struct IMFVirtualTrackResourcePlaybackCtx {
> IMFAssetLocator *locator;
> FFIMFTrackFileResource *resource;
> AVFormatContext *ctx;
> + AVRational start_time;
> + AVRational end_time;
> + AVRational ts_offset;
> } IMFVirtualTrackResourcePlaybackCtx;
>
> typedef struct IMFVirtualTrackPlaybackCtx {
> @@ -108,7 +112,6 @@ typedef struct IMFVirtualTrackPlaybackCtx {
> IMFVirtualTrackResourcePlaybackCtx *resources; /**< Buffer holding the resources */
> int32_t current_resource_index; /**< Index of the current resource in resources,
> or < 0 if a current resource has yet to be selected */
> - int64_t last_pts; /**< Last timestamp */
> } IMFVirtualTrackPlaybackCtx;
>
> typedef struct IMFContext {
> @@ -342,6 +345,7 @@ static int open_track_resource_context(AVFormatContext *s,
> int ret = 0;
> int64_t entry_point;
> AVDictionary *opts = NULL;
> + AVStream *st;
>
> if (track_resource->ctx) {
> av_log(s,
> @@ -383,23 +387,28 @@ static int open_track_resource_context(AVFormatContext *s,
> }
> av_dict_free(&opts);
>
> - /* Compare the source timebase to the resource edit rate,
> - * considering the first stream of the source file
> - */
> - if (av_cmp_q(track_resource->ctx->streams[0]->time_base,
> - av_inv_q(track_resource->resource->base.edit_rate)))
> + /* make sure there is only one stream in the file */
> +
> + if (track_resource->ctx->nb_streams != 1) {
> + ret = AVERROR_INVALIDDATA;
> + goto cleanup;
> + }
> +
> + 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 %d/%d regarding resource edit rate: %d/%d",
> - track_resource->ctx->streams[0]->time_base.num,
> - track_resource->ctx->streams[0]->time_base.den,
> + "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 = (int64_t)track_resource->resource->base.entry_point
> - * track_resource->resource->base.edit_rate.den
> - * AV_TIME_BASE
> - / 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,
> @@ -407,7 +416,7 @@ static int open_track_resource_context(AVFormatContext *s,
> "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, -1, entry_point, entry_point, entry_point, 0);
> + ret = avformat_seek_file(track_resource->ctx, 0, entry_point, entry_point, entry_point, 0);
> if (ret < 0) {
> av_log(s,
> AV_LOG_ERROR,
> @@ -470,11 +479,16 @@ static int open_track_file_resource(AVFormatContext *s,
> vt_ctx.locator = asset_locator;
> vt_ctx.resource = track_file_resource;
> vt_ctx.ctx = NULL;
> - track->resources[track->resource_count++] = vt_ctx;
> - track->duration = av_add_q(track->duration,
> + vt_ctx.start_time = track->duration;
> + vt_ctx.ts_offset = av_sub_q(vt_ctx.start_time,
> + av_div_q(av_make_q((int)track_file_resource->base.entry_point, 1),
> + track_file_resource->base.edit_rate));
> + vt_ctx.end_time = av_add_q(track->duration,
> av_make_q((int)track_file_resource->base.duration
> * track_file_resource->base.edit_rate.den,
> track_file_resource->base.edit_rate.num));
> + track->resources[track->resource_count++] = vt_ctx;
> + track->duration = vt_ctx.end_time;
> }
>
> return 0;
> @@ -701,11 +715,14 @@ static IMFVirtualTrackPlaybackCtx *get_next_track_with_minimum_timestamp(AVForma
> return track;
> }
>
> -static IMFVirtualTrackResourcePlaybackCtx *get_resource_context_for_timestamp(AVFormatContext *s,
> - IMFVirtualTrackPlaybackCtx *track)
> +static int get_resource_context_for_timestamp(AVFormatContext *s, IMFVirtualTrackPlaybackCtx *track, IMFVirtualTrackResourcePlaybackCtx **resource)
> {
> - AVRational edit_unit_duration = av_inv_q(track->resources[0].resource->base.edit_rate);
> - AVRational cumulated_duration = av_make_q(0, edit_unit_duration.den);
> + *resource = NULL;
> +
> + if (av_cmp_q(track->current_timestamp, track->duration) >= 0) {
> + av_log(s, AV_LOG_DEBUG, "Reached the end of the virtual track\n");
> + return AVERROR_EOF;
> + }
>
> av_log(s,
> AV_LOG_DEBUG,
> @@ -714,119 +731,141 @@ static IMFVirtualTrackResourcePlaybackCtx *get_resource_context_for_timestamp(AV
> av_q2d(track->current_timestamp),
> av_q2d(track->duration));
> for (uint32_t i = 0; i < track->resource_count; ++i) {
> - cumulated_duration = av_add_q(cumulated_duration,
> - av_make_q((int)track->resources[i].resource->base.duration
> - * edit_unit_duration.num,
> - edit_unit_duration.den));
>
> - if (av_cmp_q(av_add_q(track->current_timestamp, edit_unit_duration), cumulated_duration) <= 0) {
> + if (av_cmp_q(track->resources[i].end_time, track->current_timestamp) > 0) {
> av_log(s,
> AV_LOG_DEBUG,
> - "Found resource %d in track %d to read for timestamp %lf "
> - "(on cumulated=%lf): entry=%" PRIu32
> + "Found resource %d in track %d to read at timestamp %lf: "
> + "entry=%" PRIu32
> ", duration=%" PRIu32
> - ", editrate=" AVRATIONAL_FORMAT
> - " | edit_unit_duration=%lf\n",
> + ", editrate=" AVRATIONAL_FORMAT,
> i,
> track->index,
> av_q2d(track->current_timestamp),
> - av_q2d(cumulated_duration),
> track->resources[i].resource->base.entry_point,
> track->resources[i].resource->base.duration,
> - AVRATIONAL_ARG(track->resources[i].resource->base.edit_rate),
> - av_q2d(edit_unit_duration));
> + AVRATIONAL_ARG(track->resources[i].resource->base.edit_rate));
>
> if (track->current_resource_index != i) {
> + int ret;
> +
> av_log(s,
> AV_LOG_DEBUG,
> "Switch resource on track %d: re-open context\n",
> track->index);
> - if (open_track_resource_context(s, &(track->resources[i])) != 0)
> - return NULL;
> +
> + ret = open_track_resource_context(s, &(track->resources[i]));
> + if (ret != 0)
> + return ret;
> if (track->current_resource_index > 0)
> avformat_close_input(&track->resources[track->current_resource_index].ctx);
> track->current_resource_index = i;
> }
>
> - return &(track->resources[track->current_resource_index]);
> + *resource = &(track->resources[track->current_resource_index]);
> + return 0;
> }
> }
> - return NULL;
> +
> + av_log(s, AV_LOG_ERROR, "Could not find IMF track resource to read\n");
> + return AVERROR_STREAM_NOT_FOUND;
> +}
> +
> +static int imf_time_to_ts(int64_t *ts, AVRational t, AVRational time_base)
> +{
> + int dst_num;
> + int dst_den;
> + AVRational r;
> +
> + r = av_div_q(t, time_base);
> +
> + if ((av_reduce(&dst_num, &dst_den, r.num, r.den, INT64_MAX) != 1))
> + return 0;
> +
> + if (dst_den != 1)
> + return 0;
> +
> + *ts = dst_num;
> +
> + return 1;
> }
>
> static int imf_read_packet(AVFormatContext *s, AVPacket *pkt)
> {
> - IMFContext *c = s->priv_data;
> - IMFVirtualTrackResourcePlaybackCtx *resource_to_read = NULL;
> - AVRational edit_unit_duration;
> + IMFVirtualTrackResourcePlaybackCtx *resource = NULL;
> int ret = 0;
> IMFVirtualTrackPlaybackCtx *track;
> - FFStream *track_stream;
> + int64_t delta_ts;
> + AVStream *st;
> + AVRational next_timestamp;
>
> track = get_next_track_with_minimum_timestamp(s);
>
> - if (av_cmp_q(track->current_timestamp, track->duration) == 0)
> - return AVERROR_EOF;
> + ret = get_resource_context_for_timestamp(s, track, &resource);
> + if (ret)
> + return ret;
>
> - resource_to_read = get_resource_context_for_timestamp(s, track);
> + ret = av_read_frame(resource->ctx, pkt);
> + if (ret) {
> + av_log(s, AV_LOG_ERROR, "Failed to read frame\n");
> + return ret;
> + }
>
> - if (!resource_to_read) {
> - edit_unit_duration
> - = av_inv_q(track->resources[track->current_resource_index].resource->base.edit_rate);
> + av_log(s, AV_LOG_DEBUG, "Got packet: pts=%" PRId64 ", dts=%" PRId64
> + ", duration=%" PRId64 ", stream_index=%d, pos=%" PRId64
> + ", time_base=" AVRATIONAL_FORMAT "\n", pkt->pts, pkt->dts, pkt->duration,
> + pkt->stream_index, pkt->pos, pkt->time_base.num, pkt->time_base.den);
>
> - if (av_cmp_q(av_add_q(track->current_timestamp, edit_unit_duration), track->duration) > 0)
> - return AVERROR_EOF;
> + /* IMF resources contain only one stream */
>
> - av_log(s, AV_LOG_ERROR, "Could not find IMF track resource to read\n");
> - return AVERROR_STREAM_NOT_FOUND;
> - }
> + if (pkt->stream_index != 0)
> + return AVERROR_INVALIDDATA;
> + st = resource->ctx->streams[0];
>
> - while (!ff_check_interrupt(c->interrupt_callback) && !ret) {
> - ret = av_read_frame(resource_to_read->ctx, pkt);
> - av_log(s,
> - AV_LOG_DEBUG,
> - "Got packet: pts=%" PRId64
> - ", dts=%" PRId64
> - ", duration=%" PRId64
> - ", stream_index=%d, pos=%" PRId64
> - "\n",
> - pkt->pts,
> - pkt->dts,
> - pkt->duration,
> - pkt->stream_index,
> - pkt->pos);
> -
> - track_stream = ffstream(s->streams[track->index]);
> - if (ret >= 0) {
> - /* Update packet info from track */
> - if (pkt->dts < track_stream->cur_dts && track->last_pts > 0)
> - pkt->dts = track_stream->cur_dts;
> -
> - pkt->pts = track->last_pts;
> - pkt->dts = pkt->dts
> - - (int64_t)track->resources[track->current_resource_index].resource->base.entry_point;
> - pkt->stream_index = track->index;
> -
> - /* Update track cursors */
> - track->current_timestamp
> - = av_add_q(track->current_timestamp,
> - av_make_q((int)pkt->duration
> - * resource_to_read->ctx->streams[0]->time_base.num,
> - resource_to_read->ctx->streams[0]->time_base.den));
> - track->last_pts += pkt->duration;
> + pkt->stream_index = track->index;
>
> - return 0;
> - } else if (ret != AVERROR_EOF) {
> - av_log(s,
> - AV_LOG_ERROR,
> - "Could not get packet from track %d: %s\n",
> - track->index,
> - av_err2str(ret));
> - return ret;
> + /* adjust the packet PTS and DTS based on the temporal position of the resource within the timeline */
> +
> + if ((imf_time_to_ts(&delta_ts, resource->ts_offset, st->time_base) == 0))
> + av_log(s, AV_LOG_WARNING, "Incoherent time stamp " AVRATIONAL_FORMAT " for time base " AVRATIONAL_FORMAT,
> + resource->ts_offset.num, resource->ts_offset.den, pkt->time_base.num,
> + pkt->time_base.den);
> + if (pkt->pts != AV_NOPTS_VALUE)
> + pkt->pts += delta_ts;
> + if (pkt->dts != AV_NOPTS_VALUE)
> + pkt->dts += delta_ts;
> +
> + /* advance the track timestamp by the packet duration */
> +
> + next_timestamp = av_add_q(track->current_timestamp,
> + av_mul_q(av_make_q((int)pkt->duration, 1), st->time_base));
> +
> + /* if necessary, clamp the next timestamp to the end of the current resource */
> +
> + if (av_cmp_q(next_timestamp, resource->end_time) > 0) {
> +
> + next_timestamp = resource->end_time;
> +
> + /* shrink the packet duration */
> +
> + if ((imf_time_to_ts(&pkt->duration, av_sub_q(resource->end_time, track->current_timestamp), st->time_base) == 0))
> + av_log(s, AV_LOG_WARNING, "Incoherent time base during packet duration calculation");
> +
> + /* shrink the packet size itself for audio samples */
> + /* only AV_CODEC_ID_PCM_S24LE is supported in IMF */
> +
> + if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S24LE) {
> + int bytes_per_sample = av_get_exact_bits_per_sample(st->codecpar->codec_id) >> 3;
> + int64_t nbsamples = av_rescale_q(pkt->duration, st->time_base, av_make_q(1, st->codecpar->sample_rate));
> + av_shrink_packet(pkt, nbsamples * st->codecpar->channels * bytes_per_sample);
> + } else {
> + av_log(s, AV_LOG_WARNING, "Cannot shrink packets for non-PCM essence");
AV_PKT_DATA_SKIP_SAMPLES
> }
> }
>
> - return AVERROR_EOF;
> + track->current_timestamp = next_timestamp;
> +
> + return 0;
> }
>
> static int imf_close(AVFormatContext *s)
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