[FFmpeg-devel] Create and populate AVStream side data packet with contents of ISOBMFF edit list entries
Matthew Szatmary
matt at szatmary.org
Thu Jul 30 01:56:05 EEST 2020
On Wed, Jul 29, 2020 at 12:22 PM Andreas Rheinhardt
<andreas.rheinhardt at gmail.com> wrote:
>
> Matthew Szatmary:
> > Create and populate AVStream side data packet with contents of ISOBMFF
> > edit list entries
> >
> > Signed-off-by: Matthew Szatmary <matt at szatmary.org>
> > ---
> > Changelog | 1 +
> > libavcodec/packet.h | 14 ++++++++++++++
> > libavformat/mov.c | 17 ++++++++++++++++-
> > 3 files changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/Changelog b/Changelog
> > index c37ffa82e1..2d719dd3b1 100644
> > --- a/Changelog
> > +++ b/Changelog
> > @@ -9,6 +9,7 @@ version <next>:
> > - VDPAU accelerated HEVC 10/12bit decoding
> > - ADPCM IMA Ubisoft APM encoder
> > - Rayman 2 APM muxer
> > +- AV_PKT_DATA_EDIT_LIST added to AVStream side_data
> >
> >
> > version 4.3:
> > diff --git a/libavcodec/packet.h b/libavcodec/packet.h
> > index 0a19a0eff3..5faa594cf5 100644
> > --- a/libavcodec/packet.h
> > +++ b/libavcodec/packet.h
> > @@ -290,6 +290,20 @@ enum AVPacketSideDataType {
> > */
> > AV_PKT_DATA_S12M_TIMECODE,
> >
> > + /**
> > + * ISO media file edit list side data packet
> > + * The structure is repeated for each entry in the edit list
> > + * The number of entries can be calculated
> > + * by dividing the packet size by the entry size
> > + * Each entry is 20 bytes and is laid out as follows:
> > + * @code
> > + * s64le duration
> > + * s64le time
> > + * float32le rate
Good point, I will make that change.
>
> You are obviously copying the MOVElst structure; yet the rate is a 16.16
> fixed point number in the file and not a float, so one should probably
> use this.
>
> > + * @endcode
> > + */
> > + AV_PKT_DATA_EDIT_LIST,
> > +
> > /**
> > * The number of side data types.
> > * This is not part of the public API/ABI in the sense that it may
> > diff --git a/libavformat/mov.c b/libavformat/mov.c
> > index d16840f3df..bb2c940e80 100644
> > --- a/libavformat/mov.c
> > +++ b/libavformat/mov.c
> > @@ -4317,7 +4317,6 @@ static int mov_read_trak(MOVContext *c,
> > AVIOContext *pb, MOVAtom atom)
> > av_freep(&sc->keyframes);
> > av_freep(&sc->stts_data);
> > av_freep(&sc->stps_data);
> > - av_freep(&sc->elst_data);
>
> This is still needed, namely if an error happens before you can attach
> the stream side-data. E.g. if an invalid edit list is found and
> standards compliance is set to strict. Or if av_stream_new_side_data()
> fails.
av_freep(&sc->elst_data); is also called in mov_read_close, So it
would only leak if the API was used incorrectly. But that said, I
think I can move the logic to mov_read_trak, and make the whole point
moot. I was just trying to keep it near the other side_data calls.
>
> > av_freep(&sc->rap_group);
> >
> > return 0;
> > @@ -7662,6 +7661,22 @@ static int mov_read_header(AVFormatContext *s)
> > AVStream *st = s->streams[i];
> > MOVStreamContext *sc = st->priv_data;
> >
> > + if (sc->elst_data) {
> > + uint8_t *elst_data;
> > + elst_data = av_stream_new_side_data(st,
> > AV_PKT_DATA_EDIT_LIST, sc->elst_count * 20);
>
> I wonder whether it would be advantageouos to use
> av_stream_add_side_data() here.
av_stream_new_side_data is just a wrapper for av_malloc +
av_stream_add_side_data
> > +
> > + if (!elst_data)
> > + goto fail;
> > +
> > + for (j = 0; j < sc->elst_count; j++) {
> > + AV_WB64((elst_data+(j*20)), sc->elst_data[j].duration);
> > + AV_WB64((elst_data+(j*20)+8), sc->elst_data[j].time);
>
> "WB" stands for "Write Big-endian", yet your documentation says that it
> is supposed to be little-endian.
thanks, new patch included
>
> > + AV_WB32((elst_data+(j*20)+16), sc->elst_data[j].rate);
> > + }
> > +
> > + av_freep(&sc->elst_data);
> > + }
> > +
> > switch (st->codecpar->codec_type) {
> > case AVMEDIA_TYPE_AUDIO:
> > err = ff_replaygain_export(st, s->metadata);
> >
>
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Create and populate AVStream side data packet with contents of ISOBMFF
edit list entries
Signed-off-by: Matthew Szatmary <matt at szatmary.org>
---
Changelog | 1 +
libavcodec/packet.h | 15 +++++++++++++++
libavformat/mov.c | 15 +++++++++++++++
3 files changed, 31 insertions(+)
diff --git a/Changelog b/Changelog
index 6f648bff2b..d51e836301 100644
--- a/Changelog
+++ b/Changelog
@@ -10,6 +10,7 @@ version <next>:
- ADPCM IMA Ubisoft APM encoder
- Rayman 2 APM muxer
- AV1 encoding support SVT-AV1
+- AV_PKT_DATA_EDIT_LIST added to AVStream side_data
version 4.3:
diff --git a/libavcodec/packet.h b/libavcodec/packet.h
index 0a19a0eff3..1f0e3405ed 100644
--- a/libavcodec/packet.h
+++ b/libavcodec/packet.h
@@ -290,6 +290,21 @@ enum AVPacketSideDataType {
*/
AV_PKT_DATA_S12M_TIMECODE,
+ /**
+ * ISO media file edit list side data packet
+ * The structure is repeated for each entry in the edit list
+ * The number of entries can be calculated
+ * by dividing the packet size by the entry size
+ * Each entry is 20 bytes and is laid out as follows:
+ * @code
+ * s64be segment duration
+ * s64be media time
+ * s16be media rate
+ * s16be media rate fraction
+ * @endcode
+ */
+ AV_PKT_DATA_EDIT_LIST,
+
/**
* The number of side data types.
* This is not part of the public API/ABI in the sense that it may
diff --git a/libavformat/mov.c b/libavformat/mov.c
index d16840f3df..fbfcdddf3f 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -4311,6 +4311,21 @@ static int mov_read_trak(MOVContext *c,
AVIOContext *pb, MOVAtom atom)
&& sc->time_scale == st->codecpar->sample_rate) {
st->need_parsing = AVSTREAM_PARSE_FULL;
}
+
+ if (sc->elst_data) {
+ int i;
+ uint8_t *elst_data;
+ elst_data = av_stream_new_side_data(st,
AV_PKT_DATA_EDIT_LIST, sc->elst_count * 20);
+ if (elst_data) {
+ for (i = 0; i < sc->elst_count; i++) {
+ uint32_t media_rate =
(uint32_t)(sc->elst_data[i].rate * 65536.0);
+ AV_WB64((elst_data+(i*20)), sc->elst_data[i].duration);
+ AV_WB64((elst_data+(i*20)+8), sc->elst_data[i].time);
+ AV_WB32((elst_data+(i*20)+16), media_rate);
+ }
+ }
+ }
+
/* Do not need those anymore. */
av_freep(&sc->chunk_offsets);
av_freep(&sc->sample_sizes);
--
2.27.0
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