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.
This prevents sub-muxers from trying to seek back to the beginning of the
whole stream, only to find themselves overwriting some video data in the
current (often last) segment.
We only do this when not writing individual header/trailers.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This permits some interesting segmenting techniques with formats like Matroska,
where you can concatenate the header and segments [N, nb_segments) and get
a working file that starts at segment N's start time.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
A failure in segment_end() or segment_start() would lead to freeing
a dangling pointer and in general further calls to seg_write_packet()
or to seg_write_trailer() would have the same faulty behaviour.
CC: libav-stable@libav.org
Reported-By: luodalongde@gmail.com
Allows expansion of the filename template with strftime() with the option
-strftime 1 (disabled by default). This allows segments to be named by time of
creation, adding some flexibility.
Fixes Ticket 4104 (add strftime to segment muxer)
Signed-off-by: Pedro E. M. Brito <pedroembrito@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This fixes the abnormally high ts overhead in the files produced by the
HLS and segments muxers. See https://trac.ffmpeg.org/ticket/2857 . For
example makes it much more likely that it can produces streams that fit
under the 64kb App store limit.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This avoids having to assign oformat, allows returning the
correct error code and allocates priv_data
Based on patch by: Mika Raento <mika.raento@elisa.fi>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Rodger Combs
Michael Niedermayer
Marton Balint
Stefano Sabatini
Martin Vignali
Anton Khirnov
Lvqier
Clément Bœsch
Carl Eugen Hoyos
Ronald S. Bultje
Vittorio Giovara
Michael Niedermayer
Diego Biurrun
Luca Barbato
Pedro E. M. Brito
Mika Raento
Martin Storsjö
Mika Raento
Gabriel Dume