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/nutenc.c b/libavformat/nutenc.c
index 7b69ff3099..bf23b58a3b 100644
--- a/libavformat/nutenc.c
+++ b/libavformat/nutenc.c
@@ -33,32 +33,32 @@
 #include "avio_internal.h"
 #include "riff.h"
 
-static int find_expected_header(AVCodecContext *c, int size, int key_frame,
+static int find_expected_header(AVCodecParameters *p, int size, int key_frame,
                                 uint8_t out[64])
 {
-    int sample_rate = c->sample_rate;
+    int sample_rate = p->sample_rate;
 
     if (size > 4096)
         return 0;
 
     AV_WB24(out, 1);
 
-    if (c->codec_id == AV_CODEC_ID_MPEG4) {
+    if (p->codec_id == AV_CODEC_ID_MPEG4) {
         if (key_frame) {
             return 3;
         } else {
             out[3] = 0xB6;
             return 4;
         }
-    } else if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO ||
-               c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
+    } else if (p->codec_id == AV_CODEC_ID_MPEG1VIDEO ||
+               p->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
         return 3;
-    } else if (c->codec_id == AV_CODEC_ID_H264) {
+    } else if (p->codec_id == AV_CODEC_ID_H264) {
         return 3;
-    } else if (c->codec_id == AV_CODEC_ID_MP3 ||
-               c->codec_id == AV_CODEC_ID_MP2) {
+    } else if (p->codec_id == AV_CODEC_ID_MP3 ||
+               p->codec_id == AV_CODEC_ID_MP2) {
         int lsf, mpeg25, sample_rate_index, bitrate_index, frame_size;
-        int layer           = c->codec_id == AV_CODEC_ID_MP3 ? 3 : 2;
+        int layer           = p->codec_id == AV_CODEC_ID_MP3 ? 3 : 2;
         unsigned int header = 0xFFF00000;
 
         lsf           = sample_rate < (24000 + 32000) / 2;
@@ -103,13 +103,13 @@ static int find_expected_header(AVCodecContext *c, int size, int key_frame,
     return 0;
 }
 
-static int find_header_idx(AVFormatContext *s, AVCodecContext *c, int size,
+static int find_header_idx(AVFormatContext *s, AVCodecParameters *p, int size,
                            int frame_type)
 {
     NUTContext *nut = s->priv_data;
     uint8_t out[64];
     int i;
-    int len = find_expected_header(c, size, frame_type, out);
+    int len = find_expected_header(p, size, frame_type, out);
 
     for (i = 1; i < nut->header_count; i++) {
         if (len == nut->header_len[i] && !memcmp(out, nut->header[i], len)) {
@@ -169,9 +169,9 @@ static void build_frame_code(AVFormatContext *s)
     for (stream_id = 0; stream_id < s->nb_streams; stream_id++) {
         int start2 = start + (end - start) * stream_id       / s->nb_streams;
         int end2   = start + (end - start) * (stream_id + 1) / s->nb_streams;
-        AVCodecContext *codec = s->streams[stream_id]->codec;
-        const AVCodecDescriptor *desc = avcodec_descriptor_get(codec->codec_id);
-        int is_audio          = codec->codec_type == AVMEDIA_TYPE_AUDIO;
+        AVCodecParameters *par = s->streams[stream_id]->codecpar;
+        const AVCodecDescriptor *desc = avcodec_descriptor_get(par->codec_id);
+        int is_audio          = par->codec_type == AVMEDIA_TYPE_AUDIO;
         int intra_only        = /*codec->intra_only || */ is_audio;
         int pred_count;
 
@@ -183,7 +183,7 @@ static void build_frame_code(AVFormatContext *s)
                 ft->stream_id = stream_id;
                 ft->size_mul  = 1;
                 if (is_audio)
-                    ft->header_idx = find_header_idx(s, codec, -1, key_frame);
+                    ft->header_idx = find_header_idx(s, par, -1, key_frame);
                 start2++;
             }
         }
@@ -193,11 +193,11 @@ static void build_frame_code(AVFormatContext *s)
             int frame_bytes;
             int pts;
 
-            if (codec->block_align > 0) {
-                frame_bytes = codec->block_align;
+            if (par->block_align > 0) {
+                frame_bytes = par->block_align;
             } else {
-                int frame_size = av_get_audio_frame_duration(codec, 0);
-                frame_bytes = frame_size * (int64_t)codec->bit_rate / (8 * codec->sample_rate);
+                int frame_size = av_get_audio_frame_duration2(par, 0);
+                frame_bytes = frame_size * (int64_t)par->bit_rate / (8 * par->sample_rate);
             }
 
             for (pts = 0; pts < 2; pts++)
@@ -208,7 +208,7 @@ static void build_frame_code(AVFormatContext *s)
                     ft->size_mul   = frame_bytes + 2;
                     ft->size_lsb   = frame_bytes + pred;
                     ft->pts_delta  = pts;
-                    ft->header_idx = find_header_idx(s, codec, frame_bytes + pred, key_frame);
+                    ft->header_idx = find_header_idx(s, par, frame_bytes + pred, key_frame);
                     start2++;
                 }
         } else {
@@ -227,7 +227,7 @@ static void build_frame_code(AVFormatContext *s)
             pred_table[2] = 1;
             pred_table[3] = 3;
             pred_table[4] = 4;
-        } else if (codec->codec_id == AV_CODEC_ID_VORBIS) {
+        } else if (par->codec_id == AV_CODEC_ID_VORBIS) {
             pred_count    = 3;
             pred_table[0] = 2;
             pred_table[1] = 9;
@@ -251,7 +251,7 @@ static void build_frame_code(AVFormatContext *s)
                 ft->size_lsb  = index - start3;
                 ft->pts_delta = pred_table[pred];
                 if (is_audio)
-                    ft->header_idx = find_header_idx(s, codec, -1, key_frame);
+                    ft->header_idx = find_header_idx(s, par, -1, key_frame);
             }
         }
     }
@@ -424,12 +424,12 @@ static int write_streamheader(AVFormatContext *avctx, AVIOContext *bc,
                               AVStream *st, int i)
 {
     NUTContext *nut       = avctx->priv_data;
-    AVCodecContext *codec = st->codec;
-    const AVCodecDescriptor *desc = avcodec_descriptor_get(codec->codec_id);
-    unsigned codec_tag    = av_codec_get_tag(ff_nut_codec_tags, codec->codec_id);
+    AVCodecParameters *par = st->codecpar;
+    const AVCodecDescriptor *desc = avcodec_descriptor_get(par->codec_id);
+    unsigned codec_tag    = av_codec_get_tag(ff_nut_codec_tags, par->codec_id);
 
     ff_put_v(bc, i);
-    switch (codec->codec_type) {
+    switch (par->codec_type) {
     case AVMEDIA_TYPE_VIDEO:
         ff_put_v(bc, 0);
         break;
@@ -445,9 +445,9 @@ static int write_streamheader(AVFormatContext *avctx, AVIOContext *bc,
     }
     ff_put_v(bc, 4);
 
-    if (av_codec_get_id(ff_nut_codec_tags, codec->codec_tag) == codec->codec_id ||
-        !codec_tag || codec->codec_id == AV_CODEC_ID_RAWVIDEO)
-        codec_tag = codec->codec_tag;
+    if (av_codec_get_id(ff_nut_codec_tags, par->codec_tag) == par->codec_id ||
+        !codec_tag || par->codec_id == AV_CODEC_ID_RAWVIDEO)
+        codec_tag = par->codec_tag;
 
     if (codec_tag) {
         avio_wl32(bc, codec_tag);
@@ -462,18 +462,18 @@ static int write_streamheader(AVFormatContext *avctx, AVIOContext *bc,
     ff_put_v(bc, (desc && desc->props & AV_CODEC_PROP_REORDER) ? 16 : 0);
     avio_w8(bc, 0); /* flags: 0x1 - fixed_fps, 0x2 - index_present */
 
-    ff_put_v(bc, codec->extradata_size);
-    avio_write(bc, codec->extradata, codec->extradata_size);
+    ff_put_v(bc, par->extradata_size);
+    avio_write(bc, par->extradata, par->extradata_size);
 
-    switch (codec->codec_type) {
+    switch (par->codec_type) {
     case AVMEDIA_TYPE_AUDIO:
-        ff_put_v(bc, codec->sample_rate);
+        ff_put_v(bc, par->sample_rate);
         ff_put_v(bc, 1);
-        ff_put_v(bc, codec->channels);
+        ff_put_v(bc, par->channels);
         break;
     case AVMEDIA_TYPE_VIDEO:
-        ff_put_v(bc, codec->width);
-        ff_put_v(bc, codec->height);
+        ff_put_v(bc, par->width);
+        ff_put_v(bc, par->height);
 
         if (st->sample_aspect_ratio.num <= 0 ||
             st->sample_aspect_ratio.den <= 0) {