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.

4 files changed, 4 insertions, 4 deletions

diff --git a/tests/ref/vsynth/vsynth1-flashsv b/tests/ref/vsynth/vsynth1-flashsv
index a4f22ce0a4..d9bad3e19e 100644
--- a/tests/ref/vsynth/vsynth1-flashsv
+++ b/tests/ref/vsynth/vsynth1-flashsv
@@ -1,4 +1,4 @@
-6675942f5cd6978f16eff5305578de27 *tests/data/fate/vsynth1-flashsv.flv
+d0ac97a2bbf78fc02718934b70d12e70 *tests/data/fate/vsynth1-flashsv.flv
 14681905 tests/data/fate/vsynth1-flashsv.flv
 947cb24ec45a453348ae6fe3fa278071 *tests/data/fate/vsynth1-flashsv.out.rawvideo
 stddev:    2.85 PSNR: 39.03 MAXDIFF:   49 bytes:  7603200/  7603200
diff --git a/tests/ref/vsynth/vsynth1-flv b/tests/ref/vsynth/vsynth1-flv
index a92658b13d..2aaa32cbf9 100644
--- a/tests/ref/vsynth/vsynth1-flv
+++ b/tests/ref/vsynth/vsynth1-flv
@@ -1,4 +1,4 @@
-202e8b9715f278497eb13476fc9abdac *tests/data/fate/vsynth1-flv.flv
+87b9e73ada2a512ffd5abec51695e44d *tests/data/fate/vsynth1-flv.flv
 636249 tests/data/fate/vsynth1-flv.flv
 5ab46d8dd01dbb1d63df2a84858a4b05 *tests/data/fate/vsynth1-flv.out.rawvideo
 stddev:    8.02 PSNR: 30.04 MAXDIFF:  105 bytes:  7603200/  7603200
diff --git a/tests/ref/vsynth/vsynth2-flashsv b/tests/ref/vsynth/vsynth2-flashsv
index de7446bb5e..75e5d8f917 100644
--- a/tests/ref/vsynth/vsynth2-flashsv
+++ b/tests/ref/vsynth/vsynth2-flashsv
@@ -1,4 +1,4 @@
-52701f9112732b42aa425129265ef499 *tests/data/fate/vsynth2-flashsv.flv
+9980ac31d9312c38e23883063c2cc269 *tests/data/fate/vsynth2-flashsv.flv
 11636526 tests/data/fate/vsynth2-flashsv.flv
 eed2322f11b95fc7abe5356306f00d97 *tests/data/fate/vsynth2-flashsv.out.rawvideo
 stddev:    1.21 PSNR: 46.42 MAXDIFF:   20 bytes:  7603200/  7603200
diff --git a/tests/ref/vsynth/vsynth2-flv b/tests/ref/vsynth/vsynth2-flv
index 818b1110b9..343ce42c5e 100644
--- a/tests/ref/vsynth/vsynth2-flv
+++ b/tests/ref/vsynth/vsynth2-flv
@@ -1,4 +1,4 @@
-1be21ea941eb8b5ef5ecde9cac40ada0 *tests/data/fate/vsynth2-flv.flv
+6336a28db20719d12dfd3a8a6950d0fc *tests/data/fate/vsynth2-flv.flv
 174657 tests/data/fate/vsynth2-flv.flv
 c6e9b6c165558d052541309e48b5f551 *tests/data/fate/vsynth2-flv.out.rawvideo
 stddev:    6.02 PSNR: 32.53 MAXDIFF:   83 bytes:  7603200/  7603200