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, 23 insertions, 23 deletions

diff --git a/libavformat/rmenc.c b/libavformat/rmenc.c
index bbfd550a3b..e4a0d60a42 100644
--- a/libavformat/rmenc.c
+++ b/libavformat/rmenc.c
@@ -33,7 +33,7 @@ typedef struct StreamInfo {
     int nb_frames;    /* current frame number */
     int total_frames; /* total number of frames */
     int num;
-    AVCodecContext *enc;
+    AVCodecParameters *par;
 } StreamInfo;
 
 typedef struct RMMuxContext {
@@ -147,7 +147,7 @@ static int rv10_write_header(AVFormatContext *ctx,
 
         stream = &rm->streams[i];
 
-        if (stream->enc->codec_type == AVMEDIA_TYPE_AUDIO) {
+        if (stream->par->codec_type == AVMEDIA_TYPE_AUDIO) {
             desc = "The Audio Stream";
             mimetype = "audio/x-pn-realaudio";
             codec_data_size = 73;
@@ -183,11 +183,11 @@ static int rv10_write_header(AVFormatContext *ctx,
         put_str8(s, mimetype);
         avio_wb32(s, codec_data_size);
 
-        if (stream->enc->codec_type == AVMEDIA_TYPE_AUDIO) {
+        if (stream->par->codec_type == AVMEDIA_TYPE_AUDIO) {
             int coded_frame_size, fscode, sample_rate;
-            int frame_size = av_get_audio_frame_duration(stream->enc, 0);
-            sample_rate = stream->enc->sample_rate;
-            coded_frame_size = (stream->enc->bit_rate *
+            int frame_size = av_get_audio_frame_duration2(stream->par, 0);
+            sample_rate = stream->par->sample_rate;
+            coded_frame_size = (stream->par->bit_rate *
                                 frame_size) / (8 * sample_rate);
             /* audio codec info */
             avio_write(s, ".ra", 3);
@@ -228,13 +228,13 @@ static int rv10_write_header(AVFormatContext *ctx,
             /* frame length : seems to be very important */
             avio_wb16(s, coded_frame_size);
             avio_wb32(s, 0); /* unknown */
-            avio_wb16(s, stream->enc->sample_rate); /* sample rate */
+            avio_wb16(s, stream->par->sample_rate); /* sample rate */
             avio_wb32(s, 0x10); /* unknown */
-            avio_wb16(s, stream->enc->channels);
+            avio_wb16(s, stream->par->channels);
             put_str8(s, "Int0"); /* codec name */
-            if (stream->enc->codec_tag) {
+            if (stream->par->codec_tag) {
                 avio_w8(s, 4); /* tag length */
-                avio_wl32(s, stream->enc->codec_tag);
+                avio_wl32(s, stream->par->codec_tag);
             } else {
                 av_log(ctx, AV_LOG_ERROR, "Invalid codec tag\n");
                 return -1;
@@ -247,12 +247,12 @@ static int rv10_write_header(AVFormatContext *ctx,
             /* video codec info */
             avio_wb32(s,34); /* size */
             ffio_wfourcc(s, "VIDO");
-            if(stream->enc->codec_id == AV_CODEC_ID_RV10)
+            if(stream->par->codec_id == AV_CODEC_ID_RV10)
                 ffio_wfourcc(s,"RV10");
             else
                 ffio_wfourcc(s,"RV20");
-            avio_wb16(s, stream->enc->width);
-            avio_wb16(s, stream->enc->height);
+            avio_wb16(s, stream->par->width);
+            avio_wb16(s, stream->par->height);
             avio_wb16(s, (int) stream->frame_rate); /* frames per seconds ? */
             avio_wb32(s,0);     /* unknown meaning */
             avio_wb16(s, (int) stream->frame_rate);  /* unknown meaning */
@@ -261,7 +261,7 @@ static int rv10_write_header(AVFormatContext *ctx,
             /* Seems to be the codec version: only use basic H263. The next
                versions seems to add a diffential DC coding as in
                MPEG... nothing new under the sun */
-            if(stream->enc->codec_id == AV_CODEC_ID_RV10)
+            if(stream->par->codec_id == AV_CODEC_ID_RV10)
                 avio_wb32(s,0x10000000);
             else
                 avio_wb32(s,0x20103001);
@@ -312,25 +312,25 @@ static int rm_write_header(AVFormatContext *s)
     RMMuxContext *rm = s->priv_data;
     StreamInfo *stream;
     int n;
-    AVCodecContext *codec;
+    AVCodecParameters *par;
 
     for(n=0;n<s->nb_streams;n++) {
         AVStream *st = s->streams[n];
         int frame_size;
 
         s->streams[n]->id = n;
-        codec = s->streams[n]->codec;
+        par = s->streams[n]->codecpar;
         stream = &rm->streams[n];
         memset(stream, 0, sizeof(StreamInfo));
         stream->num = n;
-        stream->bit_rate = codec->bit_rate;
-        stream->enc = codec;
+        stream->bit_rate = par->bit_rate;
+        stream->par = par;
 
-        switch(codec->codec_type) {
+        switch (par->codec_type) {
         case AVMEDIA_TYPE_AUDIO:
             rm->audio_stream = stream;
-            frame_size = av_get_audio_frame_duration(codec, 0);
-            stream->frame_rate = (float)codec->sample_rate / (float)frame_size;
+            frame_size = av_get_audio_frame_duration2(par, 0);
+            stream->frame_rate = (float)par->sample_rate / (float)frame_size;
             /* XXX: dummy values */
             stream->packet_max_size = 1024;
             stream->nb_packets = 0;
@@ -365,7 +365,7 @@ static int rm_write_audio(AVFormatContext *s, const uint8_t *buf, int size, int
 
     write_packet_header(s, stream, size, !!(flags & AV_PKT_FLAG_KEY));
 
-    if (stream->enc->codec_id == AV_CODEC_ID_AC3) {
+    if (stream->par->codec_id == AV_CODEC_ID_AC3) {
         /* for AC-3, the words seem to be reversed */
         for (i = 0; i < size; i += 2) {
             avio_w8(pb, buf[i + 1]);
@@ -428,7 +428,7 @@ static int rm_write_video(AVFormatContext *s, const uint8_t *buf, int size, int
 
 static int rm_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
-    if (s->streams[pkt->stream_index]->codec->codec_type ==
+    if (s->streams[pkt->stream_index]->codecpar->codec_type ==
         AVMEDIA_TYPE_AUDIO)
         return rm_write_audio(s, pkt->data, pkt->size, pkt->flags);
     else