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, 24 insertions, 24 deletions

diff --git a/libavformat/xwma.c b/libavformat/xwma.c
index b24cde857b..e6e72d9b52 100644
--- a/libavformat/xwma.c
+++ b/libavformat/xwma.c
@@ -75,7 +75,7 @@ static int xwma_read_header(AVFormatContext *s)
     if (!st)
         return AVERROR(ENOMEM);
 
-    ret = ff_get_wav_header(s, pb, st->codec, size);
+    ret = ff_get_wav_header(s, pb, st->codecpar, size);
     if (ret < 0)
         return ret;
     st->need_parsing = AVSTREAM_PARSE_NONE;
@@ -85,9 +85,9 @@ static int xwma_read_header(AVFormatContext *s)
      * extradata for that. Thus, ask the user for feedback, but try to go on
      * anyway.
      */
-    if (st->codec->codec_id != AV_CODEC_ID_WMAV2) {
+    if (st->codecpar->codec_id != AV_CODEC_ID_WMAV2) {
         avpriv_request_sample(s, "Unexpected codec (tag 0x04%x; id %d)",
-                              st->codec->codec_tag, st->codec->codec_id);
+                              st->codecpar->codec_tag, st->codecpar->codec_id);
     } else {
         /* In all xWMA files I have seen, there is no extradata. But the WMA
          * codecs require extradata, so we provide our own fake extradata.
@@ -96,37 +96,37 @@ static int xwma_read_header(AVFormatContext *s)
          * there was, then try to use it, after asking the user to provide a
          * sample of this unusual file.
          */
-        if (st->codec->extradata_size != 0) {
+        if (st->codecpar->extradata_size != 0) {
             /* Surprise, surprise: We *did* get some extradata. No idea
              * if it will work, but just go on and try it, after asking
              * the user for a sample.
              */
             avpriv_request_sample(s, "Unexpected extradata (%d bytes)",
-                                  st->codec->extradata_size);
+                                  st->codecpar->extradata_size);
         } else {
-            st->codec->extradata_size = 6;
-            st->codec->extradata      = av_mallocz(6 + AV_INPUT_BUFFER_PADDING_SIZE);
-            if (!st->codec->extradata)
+            st->codecpar->extradata_size = 6;
+            st->codecpar->extradata      = av_mallocz(6 + AV_INPUT_BUFFER_PADDING_SIZE);
+            if (!st->codecpar->extradata)
                 return AVERROR(ENOMEM);
 
             /* setup extradata with our experimentally obtained value */
-            st->codec->extradata[4] = 31;
+            st->codecpar->extradata[4] = 31;
         }
     }
 
-    if (!st->codec->channels) {
+    if (!st->codecpar->channels) {
         av_log(s, AV_LOG_WARNING, "Invalid channel count: %d\n",
-               st->codec->channels);
+               st->codecpar->channels);
         return AVERROR_INVALIDDATA;
     }
-    if (!st->codec->bits_per_coded_sample) {
+    if (!st->codecpar->bits_per_coded_sample) {
         av_log(s, AV_LOG_WARNING, "Invalid bits_per_coded_sample: %d\n",
-               st->codec->bits_per_coded_sample);
+               st->codecpar->bits_per_coded_sample);
         return AVERROR_INVALIDDATA;
     }
 
     /* set the sample rate */
-    avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
+    avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
 
     /* parse the remaining RIFF chunks */
     for (;;) {
@@ -146,7 +146,7 @@ static int xwma_read_header(AVFormatContext *s)
              * number of bytes accumulated after the corresponding xWMA packet
              * is decoded in order."
              *
-             * Each packet has size equal to st->codec->block_align, which in
+             * Each packet has size equal to st->codecpar->block_align, which in
              * all cases I saw so far was always 2230. Thus, we can use the
              * dpds data to compute a seeking index.
              */
@@ -200,7 +200,7 @@ static int xwma_read_header(AVFormatContext *s)
     if (dpds_table && dpds_table_size) {
         int64_t cur_pos;
         const uint32_t bytes_per_sample
-                = (st->codec->channels * st->codec->bits_per_coded_sample) >> 3;
+                = (st->codecpar->channels * st->codecpar->bits_per_coded_sample) >> 3;
 
         /* Estimate the duration from the total number of output bytes. */
         const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1];
@@ -208,7 +208,7 @@ static int xwma_read_header(AVFormatContext *s)
         if (!bytes_per_sample) {
             av_log(s, AV_LOG_ERROR,
                    "Invalid bits_per_coded_sample %d for %d channels\n",
-                   st->codec->bits_per_coded_sample, st->codec->channels);
+                   st->codecpar->bits_per_coded_sample, st->codecpar->channels);
             ret = AVERROR_INVALIDDATA;
             goto fail;
         }
@@ -231,18 +231,18 @@ static int xwma_read_header(AVFormatContext *s)
              * an offset / timestamp pair.
              */
             av_add_index_entry(st,
-                               cur_pos + (i+1) * st->codec->block_align, /* pos */
-                               dpds_table[i] / bytes_per_sample,         /* timestamp */
-                               st->codec->block_align,                   /* size */
-                               0,                                        /* duration */
+                               cur_pos + (i+1) * st->codecpar->block_align, /* pos */
+                               dpds_table[i] / bytes_per_sample,            /* timestamp */
+                               st->codecpar->block_align,                   /* size */
+                               0,                                           /* duration */
                                AVINDEX_KEYFRAME);
         }
-    } else if (st->codec->bit_rate) {
+    } else if (st->codecpar->bit_rate) {
         /* No dpds chunk was present (or only an empty one), so estimate
          * the total duration using the average bits per sample and the
          * total data length.
          */
-        st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate;
+        st->duration = (size<<3) * st->codecpar->sample_rate / st->codecpar->bit_rate;
     }
 
 fail:
@@ -266,7 +266,7 @@ static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt)
     }
 
     /* read a single block; the default block size is 2230. */
-    size = (st->codec->block_align > 1) ? st->codec->block_align : 2230;
+    size = (st->codecpar->block_align > 1) ? st->codecpar->block_align : 2230;
     size = FFMIN(size, left);
 
     ret  = av_get_packet(s->pb, pkt, size);