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, 32 insertions, 32 deletions

diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c
index 36c39678d1..65bdcfc1ef 100644
--- a/libavformat/cafdec.c
+++ b/libavformat/cafdec.c
@@ -69,29 +69,29 @@ static int read_desc_chunk(AVFormatContext *s)
         return AVERROR(ENOMEM);
 
     /* parse format description */
-    st->codec->codec_type  = AVMEDIA_TYPE_AUDIO;
-    st->codec->sample_rate = av_int2double(avio_rb64(pb));
-    st->codec->codec_tag   = avio_rb32(pb);
+    st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
+    st->codecpar->sample_rate = av_int2double(avio_rb64(pb));
+    st->codecpar->codec_tag   = avio_rb32(pb);
     flags = avio_rb32(pb);
     caf->bytes_per_packet  = avio_rb32(pb);
-    st->codec->block_align = caf->bytes_per_packet;
+    st->codecpar->block_align = caf->bytes_per_packet;
     caf->frames_per_packet = avio_rb32(pb);
-    st->codec->channels    = avio_rb32(pb);
-    st->codec->bits_per_coded_sample = avio_rb32(pb);
+    st->codecpar->channels    = avio_rb32(pb);
+    st->codecpar->bits_per_coded_sample = avio_rb32(pb);
 
     /* calculate bit rate for constant size packets */
     if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
-        st->codec->bit_rate = (uint64_t)st->codec->sample_rate * (uint64_t)caf->bytes_per_packet * 8
-                              / (uint64_t)caf->frames_per_packet;
+        st->codecpar->bit_rate = (uint64_t)st->codecpar->sample_rate * (uint64_t)caf->bytes_per_packet * 8
+                                 / (uint64_t)caf->frames_per_packet;
     } else {
-        st->codec->bit_rate = 0;
+        st->codecpar->bit_rate = 0;
     }
 
     /* determine codec */
-    if (st->codec->codec_tag == MKBETAG('l','p','c','m'))
-        st->codec->codec_id = ff_mov_get_lpcm_codec_id(st->codec->bits_per_coded_sample, (flags ^ 0x2) | 0x4);
+    if (st->codecpar->codec_tag == MKBETAG('l','p','c','m'))
+        st->codecpar->codec_id = ff_mov_get_lpcm_codec_id(st->codecpar->bits_per_coded_sample, (flags ^ 0x2) | 0x4);
     else
-        st->codec->codec_id = ff_codec_get_id(ff_codec_caf_tags, st->codec->codec_tag);
+        st->codecpar->codec_id = ff_codec_get_id(ff_codec_caf_tags, st->codecpar->codec_tag);
     return 0;
 }
 
@@ -104,7 +104,7 @@ static int read_kuki_chunk(AVFormatContext *s, int64_t size)
     if (size < 0 || size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
         return -1;
 
-    if (st->codec->codec_id == AV_CODEC_ID_AAC) {
+    if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
         /* The magic cookie format for AAC is an mp4 esds atom.
            The lavc AAC decoder requires the data from the codec specific
            description as extradata input. */
@@ -113,13 +113,13 @@ static int read_kuki_chunk(AVFormatContext *s, int64_t size)
         strt = avio_tell(pb);
         ff_mov_read_esds(s, pb);
         skip = size - (avio_tell(pb) - strt);
-        if (skip < 0 || !st->codec->extradata ||
-            st->codec->codec_id != AV_CODEC_ID_AAC) {
+        if (skip < 0 || !st->codecpar->extradata ||
+            st->codecpar->codec_id != AV_CODEC_ID_AAC) {
             av_log(s, AV_LOG_ERROR, "invalid AAC magic cookie\n");
             return AVERROR_INVALIDDATA;
         }
         avio_skip(pb, skip);
-    } else if (st->codec->codec_id == AV_CODEC_ID_ALAC) {
+    } else if (st->codecpar->codec_id == AV_CODEC_ID_ALAC) {
 #define ALAC_PREAMBLE 12
 #define ALAC_HEADER   36
 #define ALAC_NEW_KUKI 24
@@ -131,8 +131,8 @@ static int read_kuki_chunk(AVFormatContext *s, int64_t size)
         }
         avio_read(pb, preamble, ALAC_PREAMBLE);
 
-        st->codec->extradata = av_mallocz(ALAC_HEADER + AV_INPUT_BUFFER_PADDING_SIZE);
-        if (!st->codec->extradata)
+        st->codecpar->extradata = av_mallocz(ALAC_HEADER + AV_INPUT_BUFFER_PADDING_SIZE);
+        if (!st->codecpar->extradata)
             return AVERROR(ENOMEM);
 
         /* For the old style cookie, we skip 12 bytes, then read 36 bytes.
@@ -142,26 +142,26 @@ static int read_kuki_chunk(AVFormatContext *s, int64_t size)
         if (!memcmp(&preamble[4], "frmaalac", 8)) {
             if (size < ALAC_PREAMBLE + ALAC_HEADER) {
                 av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
-                av_freep(&st->codec->extradata);
+                av_freep(&st->codecpar->extradata);
                 return AVERROR_INVALIDDATA;
             }
-            avio_read(pb, st->codec->extradata, ALAC_HEADER);
+            avio_read(pb, st->codecpar->extradata, ALAC_HEADER);
             avio_skip(pb, size - ALAC_PREAMBLE - ALAC_HEADER);
         } else {
-            AV_WB32(st->codec->extradata, 36);
-            memcpy(&st->codec->extradata[4], "alac", 4);
-            AV_WB32(&st->codec->extradata[8], 0);
-            memcpy(&st->codec->extradata[12], preamble, 12);
-            avio_read(pb, &st->codec->extradata[24], ALAC_NEW_KUKI - 12);
+            AV_WB32(st->codecpar->extradata, 36);
+            memcpy(&st->codecpar->extradata[4], "alac", 4);
+            AV_WB32(&st->codecpar->extradata[8], 0);
+            memcpy(&st->codecpar->extradata[12], preamble, 12);
+            avio_read(pb, &st->codecpar->extradata[24], ALAC_NEW_KUKI - 12);
             avio_skip(pb, size - ALAC_NEW_KUKI);
         }
-        st->codec->extradata_size = ALAC_HEADER;
+        st->codecpar->extradata_size = ALAC_HEADER;
     } else {
-        st->codec->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
-        if (!st->codec->extradata)
+        st->codecpar->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
+        if (!st->codecpar->extradata)
             return AVERROR(ENOMEM);
-        avio_read(pb, st->codec->extradata, size);
-        st->codec->extradata_size = size;
+        avio_read(pb, st->codecpar->extradata, size);
+        st->codecpar->extradata_size = size;
     }
 
     return 0;
@@ -309,7 +309,7 @@ static int read_header(AVFormatContext *s)
         if (caf->data_size > 0)
             st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;
     } else if (st->nb_index_entries) {
-        st->codec->bit_rate = st->codec->sample_rate * caf->data_size * 8 /
+        st->codecpar->bit_rate = st->codecpar->sample_rate * caf->data_size * 8 /
                               st->duration;
     } else {
         av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "
@@ -317,7 +317,7 @@ static int read_header(AVFormatContext *s)
         return AVERROR_INVALIDDATA;
     }
 
-    avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
+    avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
     st->start_time = 0;
 
     /* position the stream at the start of data */