This makes the final file truly hybrid: Externally the file
is a regular, non-fragmented file, but internally, the fragmented
form also exists un-overwritten.
To make any use of that, first, the fragments need to be muxed in
a position independent form, i.e. with empty_moov+default_base_moof
(or the dash or cmaf meta-flags).
Making use of the fragmented form when the file is finalized is
not entirely obvious though. One can dump the contents of the
single mdat box, and get the fragmented form. (This is a neat
trick, but not something that anybody really is expected to
want to do.)
The main expected use case is accessing fragments in the form of
byte range segments, for e.g. HLS.
Previously, the start of the file would look like this:
- ftyp
- free
- moov
- (moov contents)
After finalizing the file, it would look like this:
- ftyp
- free
- mdat (previously moov)
- (moov contents)
In this form, the size and type of the original moov box were
overwritten, and the original moov contents is just leftover
as unused data in the mdat box.
To avoid this issue, the start of the file now looks like this:
- ftyp
- free
- free
- ftyp
- moov
- (moov contents)
The second, hidden ftyp box inside mdat, would normally never be
seen.
After finalizing, the difference is that the mdat box now is
extended to cover the ftyp and the whole moov including its header
(and all the following fragments).
I.e., the start of the file looks like this:
- ftyp
- free
- mdat
- ftyp
- moov
- (moov contents)
This allows accessing the "ftyp+moov" pair sequentially as such,
with a byte range - this range is untouched when finalizing,
producing the same ftyp+moov pair both while writing, when the
file is fragmented, and after finalizing, when the file is
transformed to non-fragmented externally.
Note; the sequential two "free+free" boxes may look slightly
silly; it could be tempting to make the second one an mdat
from the get-go. However, some players of fragmented mp4 (in
particular, Apple's HLS player) bail out if the initialization
segment contains an mdat box - therefore, use a free box.
It could also be possible to use just one single free box with
8 bytes of padding at the start - but that would require more
changes to the finalization logic.
For a segmenting user of the muxer, the only unclarity is how
to determine the right byte range for the internal ftyp+moov
pair. Currently, this requires parsing the muxer output and skip
past anything up to the start of the non-empty free box.
This is how images encoded with specific transfer function should be
viewed. Image viewers that doesn't support named trc metadata, will
fallback to simple gAMA value and both of those cases should produce the
same image apperance for the viewer.
Fixes: https://github.com/mpv-player/mpv/issues/13438
Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
If using the delay_moov flag in combination with hybrid_fragment
(which is a potentially problematic combination otherwise - the
ftyp box does end up hidden in the end), then we need to flush
twice to get both the moov box and the first fragment, if the
file is finished before the first fragment is completed.
If samples were available when the moov was written, chunking
for those samples has been done already, which has to be reset
here.
This is the case when not using empty_moov, when the moov box
describes the first fragment - this case was accounted for already.
But if using the delay_moov flag, then those samples also were
available when writing the moov, so chunking for them has already
been done in this case as well.
Therefore, always reset chunking here (it should be harmless to
always do it), and update the comment to clarify the cases
involved here.
Write the moov tag at the end first, before overwriting the mdat size
at the start of the file.
In case writing the final moov box fails (e.g. due to being out
of disk), we haven't broken the initial moov box yet.
Thus if writing stops between these steps, we could end up with
a file with two moov boxes - which arguably is more feasible to
recover from, than from a file with no moov boxes at all.
This reverts commit 301141b576.
cluster[0].dts, pts and frag_info[0].time are already in presentation
timeline, so they shouldn't be shift by start_pts.
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
Attempts to base the fragmentation timing on other streams
as most receivers expect media fragments to be more or less
aligned.
Currently does not support fragmentation on subtitle track
only, as the subtitle packet queue timings would have to be
checked in addition to the current fragmentation timing logic.
Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
In hybrid_fragmented mode, the first moov at start should contain
mvex tag, since it's fmp4. When writing the moov at the second time,
it's not fmp4 any more, so mvex should be skipped.
Fixes issue #20018.
Note that Codec Descriptors are not written for all these ai** codec tags, and no
considerations were ever made to ensure parameter sets are present in muxed packets.
Their usage may result in unplayable files if parameter sets are only available
in extradata (Default behavior for x264 encoding when combined with this muxer).
Signed-off-by: James Almer <jamrial@gmail.com>
If a packet contains new extradata within a side data entry, save for
specific cases it means the coded stream changed. If ignored, upon
demuxing every packet from then onwards may be undecodable.
Signed-off-by: James Almer <jamrial@gmail.com>
HEVC fmp4 HLS video produced by ffmpeg is currently unplayable on Apple
software (Safari, QuickTime, AVFoundation).
This is caused by an empty sdtp atom being erroneously written to the
fmp4 init segment. The `has_disposable` flag can be set for a track
with B-frames, but the init segment contains no actual frames
(track->entry == 0). Writing an sdtp atom in this case is incorrect
and causes Apple's parsers to reject the file.
This patch fixes the issue by ensuring the sdtp atom is only written
if track->entry is non-zero.
A similar patch was proposed in November 2023 by Jay Zhang,
but it was never merged.
Link: https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2023-November/317173.html
Co-authored-by: Jay Zhang <wangyoucao577@gmail.com>
Signed-off-by: David McElroy <david@mcelroy.online>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
- Changes in mov_write_video_tag function to handle APV elementary stream
- Provided structure APVDecoderConfigurationRecord that specifies the decoder configuration information for APV video content
Co-Authored-by: James Almer <jamrial@gmail.com>
Signed-off-by: Dawid Kozinski <d.kozinski@samsung.com>
Signed-off-by: James Almer <jamrial@gmail.com>
The segment_duration must not be set to zero when writing the moov
atom for the second time. This is related to edit lists in standard
MP4 files.
Reviewed-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
As described in section F.6.1 from ETSI TS 102 366.
Found-by: nyanmisaka
Reviewed-by: Baptiste Coudurier <baptiste.coudurier@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
The follow cmd output corrupted file before the patch:
ffmpeg -f lavfi -i color=blue,trim=duration=0.04 \
-f lavfi -i anullsrc,atrim=duration=2 \
-movflags +empty_moov+hybrid_fragmented \
-frag_duration 1000000 \
-frag_interleave 1 \
output.mp4
1. first_track is the first track with track->entry != 0. As in the
command above, video track (track index 0) has a single frame. When
flush the second fragment, first_track is 1, the audio track.
2. write_moof = i == first_track, so write_moof is false for i = 0.
3. When mov->frag_interleave != 0, mov->mdat_buf != NULL, because
it contains audio data. So avio_write is called before write_moof,
that is, the data write before moof, and mov_finish_fragment
executed with wrong mdat_start.
4. With normal fmp4 output, the error isn't obvious. With
hybrid_fragmented, ffplay output.mp4 shows a lot of error messages.
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
The default behavior for VVenC (since v1.10.0) is to create an IDR with
leading pictures for the first picture in decoding order (POC 32). This
leads to FFmpeg generating an edit list with an empty entry, skipping
the leading pictures.
This patch fixes the calculation for the start_pts, while the DTS is
negative (as produced by vvenc).
Signed-off-by: Gabriel Hege <g+ffmpeg@hege.cc>
'avs3' is registered at mp4ra.org. The Avs3ConfigurationBox 'av3c'
inside 'avs3' hasn't been registered yet, but is specified by the
AVS3 spec.
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
They are needed for audio tracks with priming samples, where negative CTS
offsets can't be used.
Fixes ticket #11031.
Signed-off-by: James Almer <jamrial@gmail.com>
avgBitrate == 0 is used to signal a VBR track, so if that value is propagated by an
encoder, don't overwrite it with a calculated value based on track size.
Part of a fix for ticket #11303.
Signed-off-by: James Almer <jamrial@gmail.com>
In some scenarios nb_tracks isn't the same as nb_streams, so a given id may end
up being used for two separate streams.
e.g. when muxing an IAMF track followed by a video track, if the IAMF track
consists of several streams, the video track would end up having an id of 2,
which may also be used by one of the IAMF streams.
Signed-off-by: James Almer <jamrial@gmail.com>
