[FFmpeg-devel] [PATCH v1 3/4] avformat/imf: fix packet pts, dts and muxing
pal at sandflow.com
pal at sandflow.com
Mon Jan 31 00:00:54 EET 2022
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");
}
}
- return AVERROR_EOF;
+ track->current_timestamp = next_timestamp;
+
+ return 0;
}
static int imf_close(AVFormatContext *s)
--
2.17.1
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