Skip to content

F
ffmpeg.wasm-core
Switch branch/tag
  1. 03 May, 2020 4 commits
    • Andreas Rheinhardt's avatar
      avformat/vorbiscomment: Replace AVDictionary ** by const AVDictionary * · 704d7c9f
      Andreas Rheinhardt authored 
      ff_vorbiscomment_write() used an AVDictionary ** parameter for a
dictionary whose contents ought to be written; yet this can be replaced
by AVDictionary * since commit 042ca05f;
and this in turn can be replaced by const AVDictionary * to indicate
that the dictionary isn't modified; the latter also applies to
ff_vorbiscomment_length().
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      704d7c9f
    • Andreas Rheinhardt's avatar
      avformat/matroskaenc: Replace impossible condition with assert · ca0a38f2
      Andreas Rheinhardt authored 
      If a FLAC track uses an unconventional channel layout, the Matroska
muxer adds a WAVEFORMATEXTENSIBLE_CHANNEL_MASK VorbisComment to the
CodecPrivate to preserve this information. And given that FLAC uses
24bit length fields, the muxer checks if the length is more than this
and errors out if it is.

Yet this can never happen, because we create the AVDictionary that is
the source for the VorbisComment. It only contains exactly one entry
that can't grow infinitely large (in fact, the length of the
VorbisComment is <= 4 + 33 + 1 + 18 + strlen(LIBAVFORMAT_IDENT)).
So we can simply assert the size to be < (1 << 24) - 4.
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      ca0a38f2
    • Andreas Rheinhardt's avatar
      avformat/matroskaenc: Write SeekHead when livestreaming · d13feae0
      Andreas Rheinhardt authored 
      Commit 6fd300ac added support for WebM
Chunk livestreaming; in this case, both the header as well as each
Cluster is written to a file of its own, so that even if the AVIOContext
seems seekable, the muxer has to behave as if it were not. Yet one of
the added checks makes no sense: It ensures that no SeekHead is written
preliminarily (and hence no SeekHead is written at all) if the option
for livestreaming is set, although one should write the SeekHead in this
case when writing the Header. E.g. the WebM-DASH specification [1]
never forbids writing a SeekHead and in some instances (that don't apply
here) even requires it (if Cues are written after the Clusters).

[1]: https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specificationSigned-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      d13feae0
    • Andreas Rheinhardt's avatar
      avformat/matroskaenc: Only write Cluster if it has in fact been opened · 68c7186d
      Andreas Rheinhardt authored 
      Since commit 4aa0665f, the dynamic
buffer destined for the contents of the current Cluster is no longer
constantly allocated, reallocated and then freed after writing the
content; instead it is reset and reused when closing a Cluster.

Yet the code in mkv_write_trailer() still checked for whether a Cluster
is open by checking whether the pointer to the dynamic buffer is NULL or
not (instead of checking whether the position of the current Cluster is
-1 or not). If a Cluster was not open, an empty Cluster would be output.

One usually does not run into this issue, because unless there are
errors, there are only three possibilities to not have an opened Cluster
at the end of writing a packet:
The first is if one sent an audio packet to the muxer. It might trigger
closing and outputting the old Cluster, but because the muxer caches
audio packets internally, it would not be output immediately and
therefore no new Cluster would be opened.
The second is an audio packet that does not contain data (such packets
are sometimes sent for side-data only, e.g. by the FLAC encoder). The
only difference to the first scenario is that such packets are not
cached.
The third is if one explicitly flushes the muxer by sending a NULL
packet via av_write_frame().

If one also allows for errors, then there is also another possibility:
Caching the audio packet may fail in the first scenario.

If one calls av_write_trailer() after the first scenario, the cached
audio packet will be output when writing the trailer, for which
a Cluster is opened and everything is fine; because flushing the muxer
does currently not output the cached audio packet (if one is cached),
the issue also does not exist if an audio packet has been cached before
flushing. The issue only exists in one of the other scenarios.
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      68c7186d
  3. 02 May, 2020 19 commits
  5. 01 May, 2020 17 commits