Commit Graph

6 Commits

Author SHA1 Message Date
Anton Khirnov
9200514ad8 lavf: replace AVStream.codec with AVStream.codecpar
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.
2016-02-23 17:01:58 +01:00
Vittorio Giovara
e80307140f yuv4mpegenc: Use AV_CEIL_RSHIFT where needed 2016-01-25 12:02:44 -05:00
Luca Barbato
d00a8fd417 yuv4mpeg: Use the wrapped avframe pseudo-encoder 2015-10-10 14:50:42 +02:00
Anton Khirnov
650d384048 yuv4mpegenc: do not access AVCodecContext.coded_frame
Its contents are meaningful only if the stream codec context is the one
actually used for encoding, which is often not the case (and is
discouraged).

Use AVCodecContext.field_order instead.
2014-07-09 13:40:39 +00:00
Anton Khirnov
194be1f43e lavf: switch to AVStream.time_base as the hint for the muxer timebase
Previously, AVStream.codec.time_base was used for that purpose, which
was quite confusing for the callers. This change also opens the path for
removing AVStream.codec.

The change in the lavf-mkv test is due to the native timebase (1/1000)
being used instead of the default one (1/90000), so the packets are now
sent to the crc muxer in the same order in which they are demuxed
(previously some of them got reordered because of inexact timestamp
conversion).
2014-06-18 15:12:34 +02:00
Anton Khirnov
e4dc1000d7 yuv4mpeg: split the demuxer and muxer into separate files 2014-05-18 10:21:31 +02:00