If the user has set none of the options specifying the segments'
durations, a default value of 2s is used by duplicating a "2" string and
using av_parse_time() on it. Yet duplicating the string was unchecked
and if the allocation failed, one would get a segfault in
av_parse_time().
This commit solves this by turning said option into an option of type
AV_OPT_TYPE_DURATION (which also uses av_parse_time() internally),
avoiding duplicating the string altogether.
Reviewed-by: Ridley Combs <rcombs@rcombs.me>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit 06f99cc4dd)
The code to free them is not in the segment muxer's deinit function,
but in its write_trailer function which means that these lists leak if
write_trailer isn't called after their allocation. This happens e.g. if
the given lists are invalid (e.g. consisting only of ',' (which delimit
entries)), so that parsing them fails and so does the muxer's init
function; write_trailer is then never called.
This has been fixed by moving the code to free them to the deinit
function.
Reviewed-by: Ridley Combs <rcombs@rcombs.me>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit 4b836c8613)
The segment muxer copies the user-provided AVCodecParameters to the
newly created child streams in its init function before initializing the
child muxer; and since commit 8e6478b723affe4d44f94d34b98e0c47f6a0b411,
it does this again before calling avformat_write_header() if that is
called from seg_write_header(). The reason for this is complicated:
At that time writing the header was delayed, i.e. it was not triggered
by avformat_write_header() (unless the AVFMT_FLAG_AUTO_BSF was unset),
but instead by writing the very first packet. The rationale behind this
was to allow to run bitstream filters on the packets in the interleavement
queue in order to generate missing extradata from them before the muxer's
write_header function is actually called.
The segment muxer went even further: It initialized the child muxer and
ran the child muxer's check_bitstream functions on the packets in its
own muxing queue and stole any bitstream filters that got inserted. The
reason for this is that the segment muxer has an option to write the
header to a separate file and for this it is needed to write the child
muxer's header without delay, but with correct extradata. Unsetting
AVFMT_FLAG_AUTO_BSF for the child muxer accomplished the first goal and
stealing the bitstream filters the second; and in order for the child
muxer to actually use the updated extradata, the old AVCodecParameters
(set before avformat_init_output()) were overwritten with the new ones.
Updating the extradata proceeded as follows: The bitstream filter itself
simply updated the AVBSFContext's par_out when processing a packet, in
violation of the new BSF API (where par_out may only be set in the init
function); the muxing code then simply forwarded the updated extradata,
overwriting the par_in of the next BSF in the BSF chain with the fresh
par_out of the last one and the AVStream's par with the par_out of the
last BSF. This was an API violation, too, of course, but it made
remuxing ADTS AAC into mp4/matroska work.
But this no longer serves a useful purpose since the aac_adtstoasc BSF
was updated to propagate new extradata via packet side data in commit
f63c3516577d605e51cf16358cbdfa0bc97565d8; the next commit then removed
the code in mux.c passing new extradata along the filter chain. This
alone justifies removing the code for setting the AVCodecParameters a
second time.
But there is even another reason to do so: It is harmful. The ogg muxer
parses the extradata of Theora and Vorbis in its init function and keeps
pointers to parts of it. Said pointers become dangling when the
extradata is overwritten by the segment muxer, leading to
use-after-frees as has happened in ticket #8881 which this commit fixes.
Ticket #8517 is about another issue caused by this: Immediately after
having overwritten the old AVCodecParameters the segment muxer checks
whether the codec_tag is ok (the codec_tag is set generically when
initializing the child muxer based upon muxer-specific lists). The check
used is: If the child output format has such a list and if the codec tag
of the non-child stream does not match the codec id given the list of
codec tags and if there is a match for the codec id in the codec tag
list, then set the codec tag to zero (and not to the existing match),
otherwise set the codec tag of the child stream to the codec tag
of the corresponding stream of the main AVFormatContext (which is btw
redundant given that the child AVCodecParameters have just been
overwritten with the AVCodecParameters of the corresponding stream of
the main AVFormatContext).
Reviewed-by: Ridley Combs <rcombs@rcombs.me>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit 92c8b79b5a)
Current muxers only use a single bitstream filter, so there is no need to
maintain code which operates on a list of bitstream filters. When multiple
bitstream filters are needed muxers can simply use a list bitstream filter.
If there is a use case in the future when different bitstream filters should be
added at subsequent packets then a new API possibly involving reconfiguring the
list bitstream filter can be added knowing the exact requirements.
Signed-off-by: Marton Balint <cus@passwd.hu>
ff_alloc_extradata() already sets the size of the extradata so doing it
again is unnecessary.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Reviewed-by: Gyan Doshi <ffmpeg@gyani.pro>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
avformat/movenc still relies on AVCodecContext time_base to mux tmcd
tracks and segment muxer did not copy that field to inner streams
leading to SIGFPE in the child muxer instance.
At present, if the outer stream extradata is empty but first packet
has extradata as a side data element, then only the first segment's
muxer instance may be able to extract this side data and use it.
For all other segments, extradata in packet side data could be missing
and generated segments may be invalid or unplayable in some apps
e.g. for an ADTS AAC stream segmented to MP4, the adtstoasc BSF will
add extradata to the first packet. The MOV muxer for the first segment
will add this to codecpar for the inner stream and write
Decoder Specific Information within the esds box. For other segments,
their esds' will not have this decSpecificInfo and they can't be opened
in Quicktime player or by services like nginx-vod-module.
Not starting a new segment if the elapsed microsecs since the start of the day
equals the the elapsed microsecs since the start of the day at the time of the
last cut seems plain wrong to me, Deti do you remember the original reason
behind this check?
Signed-off-by: Marton Balint <cus@passwd.hu>
This happens because segment_end() returns an error, so seg_write_packet
never proceeds to segment_start(), and seg->avf->pb is never re-set,
so we crash with a null pb when av_write_trailer flushes the packet
queue.
This doesn't seem to be clearly recoverable, so I'm just failing more
gracefully.
Repro:
ffmpeg -i input.ts -f segment -c copy -segment_list /noaxx.m3u8 test-%05d.ts
(assuming you don't have write access to /)
ffmpeg have a generic solution working with all muxer named
output_ts_offset, output_ts_offset will instead of initial_offset
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
because the BSF logic was re-factored into a shareable
function and both av_write_frame and av_interleaved_write_frame use it it
Signed-off-by: LiuQi <liuqi@gosun.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
For example you can split a file, keeping a continuous timecode between
each segment:
ffmpeg -i src.mov -timecode 10:00:00:00 -vcodec copy -f segment \
-segment_time 2 -reset_timestamps 1 -increment_tc 1 target_%03d.mov
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
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.
This option can force the segmenter to only start a new segment if a packet
reaches the muxer within the specified duration after the segmenting clock
time, which makes it more resilient to backward local time jumps, such as leap
seconds or transition to standard time from daylight savings time.
Reviewed-by: Stefano Sabatini <stefasab@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>
Some (de)muxers open additional files beyond the main IO context.
Currently, they call avio_open() directly, which prevents the caller
from using custom IO for such streams.
This commit adds callbacks to AVFormatContext that default to
avio_open2()/avio_close(), but can be overridden by the caller. All
muxers and demuxers using AVIO are switched to using those callbacks
instead of calling avio_open()/avio_close() directly.
(de)muxers that use the URLProtocol layer directly instead of AVIO
remain unconverted for now. This should be fixed in later commits.
Andreas Rheinhardt
Marton Balint
Paul B Mahol
Gyan Doshi
Carl Eugen Hoyos
James Almer
Lou Logan
Anton Khirnov
Tobias Rapp
Rodger Combs
Steven Liu
Michael Niedermayer
Stefano Sabatini
Martin Vignali
Lvqier
Clément Bœsch
Carl Eugen Hoyos