Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
Use av_realloc() rather than av_malloc() when normalizing noncompliant
private data in get_qt_codec().
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This patch adds a new static function get_qt_codec() that takes care of
the initial retrieval of the fourcc and codec ID for A_QUICKTIME and
V_QUICKTIME. It also normalizes noncompliant private data found in some
older files that incorrectly starts with the fourcc by expanding/shifting
the data by 4 bytes, and storing the data size at the start. This is
necessary in order for the rest of the code in the A_QUICKTIME and
V_QUICKTIME blocks (and most likely other code as well) to correctly
parse the private data.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
In many older QuickTime files, the audio format, or "fourcc", is
0x00000000. The QuickTime File Format Specification states the following
regarding this situation:
"This format descriptor should not be used, but may be found in some
files. Samples are assumed to be stored in either 'raw ' or 'twos'
format, depending on the sample size field in the sound description."
MPlayer handles this logic by itself, but FFmpeg/FFplay currently does
not.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Palettized QuickTime video in Matroska has hitherto not been recognized
whatsoever, and the "palette" used has been completely random.
The patch for matroskadec.c fixes this issue by adding a palette side
data packet in matroska_deliver_packet(), much in the same way as it's
done in mov.c.
Video samples for testing are available at
https://drive.google.com/open?id=0B3_pEBoLs0faWElmM2FnLTZYNlk.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
matroskaenc applies divisors to the display width/height when generating
stereo content. This patch adds the corresponding multipliers to matroskadec
so that the original sample aspect ratio can be recovered.
Signed-off-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
matroskaenc.c applies divisors to the display width/height when generating
stereo content. This patch adds the corresponding multipliers to matroskadec.c
so that the original sample aspect ratio can be recovered.
Signed-off-by: wm4 <nfxjfg@googlemail.com>
Unrecognized streams are not allocated
Fixes: flicker-1.color1.vp91447030769.08.webm
Found-by: Chris Cunningham <chcunningham@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Note that convergence_duration had another meaning, one which was in
practice never used. The only real use for it was a 64 bit replacement
for the duration field. It's better just to make duration 64 bits, and
to get rid of it.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
In the TTA extradata re-construction the values are written with
avio_wl16 and if they don't fit into uint16_t, this triggers an
av_assert2 in avio_w8.
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
And default to 8000 if it is invalid.
An invalid sample rate can trigger av_assert2 in av_rescale_rnd.
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Some files have SeekHead elements with broken IDs. They mismatch with
the ID of the destination element. These files are written by
"IDMmkvlib0.1" (as identified by the MuxingApp and WritingApp elements),
and the SeekHead IDs are actually endian-swapped.
This confuses the SeekHead logic of the demuxer. It will read some
elements twice, because the SeekHead ID is used to identify and remember
already read elements. With the file at hand, the stream list was
duplicated by reading the Tracks element twice.
Fix this by rejecting invalid EBML IDs in SeekHead entries. (This fix is
relatively specific to the broken file at hand, and doesn't protect
against some other cases of broken SeekHead, such as valid but
mismatching target element IDs.)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This fixes a segmentation fault.
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
index_scale is set to matroska->time_scale of type uint64_t.
When index_scale is int, the assignment can overflow and e.g. result
in index_scale = 0. This causes a floating point exception due to the
division by index_scale.
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Generally, libavformat exports cover art pictures as video streams with
1 packet and AV_DISPOSITION_ATTACHED_PIC set. Only matroskadec exported
it as attachment with codec_id set to AV_CODEC_ID_MJPEG.
Obviously, this should be consistent, so change the Matroska demuxer to
export a AV_DISPOSITION_ATTACHED_PIC pseudo video stream.
Matroska muxing is probably incorrect too. I know that it can create
broken files with an audio track and just 1 video frame when e.g.
remuxing mp3 with APIC to mkv. But for now this commit does not change
anything about muxing, and also continues to write attachments with
AV_CODEC_ID_MJPEG should the muxer application have special knowledge
that the Matroska is broken in this way.
Signed-off-by: Anton Khirnov <anton@khirnov.net>
This patch adds support for parsing live files (produced by
-f webm_chunk) which contains only the headers but no packets. This
is only used when using -f webm_dash_manifest. There will be a
follow up patch which adds live support to WebM DASH Manifest
muxer.
Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Generally, libavformat exports cover art pictures as video streams with
1 packet and AV_DISPOSITION_ATTACHED_PIC set. Only matroskadec exported
it as attachment with codec_id set to AV_CODEC_ID_MJPEG.
Obviously, this should be consistent, so change the Matroska demuxer to
export a AV_DISPOSITION_ATTACHED_PIC pseudo video stream.
Matroska muxing is probably incorrect too. I know that it can create
broken files with an audio track and just 1 video frame when e.g.
remuxing mp3 with APIC to mkv. But for now this commit does not change
anything about muxing, and also continues to write attachments with
AV_CODEC_ID_MJPEG should the muxer application have special knowledge
that the Matroska is broken in this way.
Fixes trac #4423.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Just because the user requested the seek index to be ignored, we can't
just skip essential headers. At least tags are often located at the end
of the file, and the old code simply ignored the seekhead for all
elements, not just the cue index. Also, it looks like it used the index
even if IGNIDX was set if the cue index was located in the beginning of
the file.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
In particular, this reads chained seekheads. This makes seeking faster
in files which have the index indirectly linked through 2 seekheads.
As a side-effect, this warns when reading level-1 (toplevel) elements
multiple times (other than seekheads, clusters, and void/crc). Such
elements are not valid and likely break everything.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Matroska is an extensible format - unknown elements must be expected. It
shouldn't complain about such elements to the user either; it'll just
generate noise. The "error_recognition & AV_EF_EXPLODE" is completely,
wrong why would it explode on valid files?
It's still useful for debugging, so the message is left in place with a
higher log level.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
In matroska_read_seek(), |tracks| is assigned at the begining of the
function. However, functions like matroska_parse_cues() could reallocate
the tracks and invalidate |tracks|.
This assigns |tracks| only before using it, so that it will not get
invalidated elsewhere.
Bug-Id: chromium/427266
Anton Khirnov
Luca Barbato
Mats Peterson
Carl Eugen Hoyos
Aaron Colwell
Clément Bœsch
Michael Niedermayer
Hendrik Leppkes
Rodger Combs
wm4
Vittorio Giovara
Michael Niedermayer
Andreas Cadhalpun
Thomas Guillem
Vignesh Venkatasubramanian
Diego Biurrun
Thomas Volkert
Xiaohan Wang