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.

1 files changed, 36 insertions, 36 deletions

diff --git a/libavformat/rpl.c b/libavformat/rpl.c
index fdcefdbf72..0fa940e524 100644
--- a/libavformat/rpl.c
+++ b/libavformat/rpl.c
@@ -145,35 +145,35 @@ static int rpl_read_header(AVFormatContext *s)
     vst = avformat_new_stream(s, NULL);
     if (!vst)
         return AVERROR(ENOMEM);
-    vst->codec->codec_type      = AVMEDIA_TYPE_VIDEO;
-    vst->codec->codec_tag       = read_line_and_int(pb, &error);  // video format
-    vst->codec->width           = read_line_and_int(pb, &error);  // video width
-    vst->codec->height          = read_line_and_int(pb, &error);  // video height
-    vst->codec->bits_per_coded_sample = read_line_and_int(pb, &error);  // video bits per sample
+    vst->codecpar->codec_type      = AVMEDIA_TYPE_VIDEO;
+    vst->codecpar->codec_tag       = read_line_and_int(pb, &error);  // video format
+    vst->codecpar->width           = read_line_and_int(pb, &error);  // video width
+    vst->codecpar->height          = read_line_and_int(pb, &error);  // video height
+    vst->codecpar->bits_per_coded_sample = read_line_and_int(pb, &error);  // video bits per sample
     error |= read_line(pb, line, sizeof(line));                   // video frames per second
     fps = read_fps(line, &error);
     avpriv_set_pts_info(vst, 32, fps.den, fps.num);
 
     // Figure out the video codec
-    switch (vst->codec->codec_tag) {
+    switch (vst->codecpar->codec_tag) {
 #if 0
         case 122:
-            vst->codec->codec_id = AV_CODEC_ID_ESCAPE122;
+            vst->codecpar->codec_id = AV_CODEC_ID_ESCAPE122;
             break;
 #endif
         case 124:
-            vst->codec->codec_id = AV_CODEC_ID_ESCAPE124;
+            vst->codecpar->codec_id = AV_CODEC_ID_ESCAPE124;
             // The header is wrong here, at least sometimes
-            vst->codec->bits_per_coded_sample = 16;
+            vst->codecpar->bits_per_coded_sample = 16;
             break;
         case 130:
-            vst->codec->codec_id = AV_CODEC_ID_ESCAPE130;
+            vst->codecpar->codec_id = AV_CODEC_ID_ESCAPE130;
             break;
         default:
             av_log(s, AV_LOG_WARNING,
                    "RPL video format %i not supported yet!\n",
-                   vst->codec->codec_tag);
-            vst->codec->codec_id = AV_CODEC_ID_NONE;
+                   vst->codecpar->codec_tag);
+            vst->codecpar->codec_id = AV_CODEC_ID_NONE;
     }
 
     // Audio headers
@@ -185,59 +185,59 @@ static int rpl_read_header(AVFormatContext *s)
         ast = avformat_new_stream(s, NULL);
         if (!ast)
             return AVERROR(ENOMEM);
-        ast->codec->codec_type      = AVMEDIA_TYPE_AUDIO;
-        ast->codec->codec_tag       = audio_format;
-        ast->codec->sample_rate     = read_line_and_int(pb, &error);  // audio bitrate
-        ast->codec->channels        = read_line_and_int(pb, &error);  // number of audio channels
-        ast->codec->bits_per_coded_sample = read_line_and_int(pb, &error);  // audio bits per sample
+        ast->codecpar->codec_type      = AVMEDIA_TYPE_AUDIO;
+        ast->codecpar->codec_tag       = audio_format;
+        ast->codecpar->sample_rate     = read_line_and_int(pb, &error);  // audio bitrate
+        ast->codecpar->channels        = read_line_and_int(pb, &error);  // number of audio channels
+        ast->codecpar->bits_per_coded_sample = read_line_and_int(pb, &error);  // audio bits per sample
         // At least one sample uses 0 for ADPCM, which is really 4 bits
         // per sample.
-        if (ast->codec->bits_per_coded_sample == 0)
-            ast->codec->bits_per_coded_sample = 4;
+        if (ast->codecpar->bits_per_coded_sample == 0)
+            ast->codecpar->bits_per_coded_sample = 4;
 
-        ast->codec->bit_rate = ast->codec->sample_rate *
-                               ast->codec->bits_per_coded_sample *
-                               ast->codec->channels;
+        ast->codecpar->bit_rate = ast->codecpar->sample_rate *
+                                  ast->codecpar->bits_per_coded_sample *
+                                  ast->codecpar->channels;
 
-        ast->codec->codec_id = AV_CODEC_ID_NONE;
+        ast->codecpar->codec_id = AV_CODEC_ID_NONE;
         switch (audio_format) {
             case 1:
-                if (ast->codec->bits_per_coded_sample == 16) {
+                if (ast->codecpar->bits_per_coded_sample == 16) {
                     // 16-bit audio is always signed
-                    ast->codec->codec_id = AV_CODEC_ID_PCM_S16LE;
+                    ast->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;
                     break;
                 }
                 // There are some other formats listed as legal per the spec;
                 // samples needed.
                 break;
             case 101:
-                if (ast->codec->bits_per_coded_sample == 8) {
+                if (ast->codecpar->bits_per_coded_sample == 8) {
                     // The samples with this kind of audio that I have
                     // are all unsigned.
-                    ast->codec->codec_id = AV_CODEC_ID_PCM_U8;
+                    ast->codecpar->codec_id = AV_CODEC_ID_PCM_U8;
                     break;
-                } else if (ast->codec->bits_per_coded_sample == 4) {
-                    ast->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_EA_SEAD;
+                } else if (ast->codecpar->bits_per_coded_sample == 4) {
+                    ast->codecpar->codec_id = AV_CODEC_ID_ADPCM_IMA_EA_SEAD;
                     break;
                 }
                 break;
         }
-        if (ast->codec->codec_id == AV_CODEC_ID_NONE) {
+        if (ast->codecpar->codec_id == AV_CODEC_ID_NONE) {
             av_log(s, AV_LOG_WARNING,
                    "RPL audio format %"PRId32" not supported yet!\n",
                    audio_format);
         }
-        avpriv_set_pts_info(ast, 32, 1, ast->codec->bit_rate);
+        avpriv_set_pts_info(ast, 32, 1, ast->codecpar->bit_rate);
     } else {
         for (i = 0; i < 3; i++)
             error |= read_line(pb, line, sizeof(line));
     }
 
     rpl->frames_per_chunk = read_line_and_int(pb, &error);  // video frames per chunk
-    if (rpl->frames_per_chunk > 1 && vst->codec->codec_tag != 124)
+    if (rpl->frames_per_chunk > 1 && vst->codecpar->codec_tag != 124)
         av_log(s, AV_LOG_WARNING,
                "Don't know how to split frames for video format %i. "
-               "Video stream will be broken!\n", vst->codec->codec_tag);
+               "Video stream will be broken!\n", vst->codecpar->codec_tag);
 
     number_of_chunks = read_line_and_int(pb, &error);  // number of chunks in the file
     // The number in the header is actually the index of the last chunk.
@@ -297,8 +297,8 @@ static int rpl_read_packet(AVFormatContext *s, AVPacket *pkt)
         if (avio_seek(pb, index_entry->pos, SEEK_SET) < 0)
             return AVERROR(EIO);
 
-    if (stream->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
-        stream->codec->codec_tag == 124) {
+    if (stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
+        stream->codecpar->codec_tag == 124) {
         // We have to split Escape 124 frames because there are
         // multiple frames per chunk in Escape 124 samples.
         uint32_t frame_size;
@@ -329,7 +329,7 @@ static int rpl_read_packet(AVFormatContext *s, AVPacket *pkt)
             return AVERROR(EIO);
         }
 
-        if (stream->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
+        if (stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
             // frames_per_chunk should always be one here; the header
             // parsing will warn if it isn't.
             pkt->duration = rpl->frames_per_chunk;