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, 49 insertions, 49 deletions

diff --git a/libavformat/avienc.c b/libavformat/avienc.c
index 9c2936af60..d89fab17e8 100644
--- a/libavformat/avienc.c
+++ b/libavformat/avienc.c
@@ -111,21 +111,21 @@ static int avi_write_counters(AVFormatContext *s, int riff_id)
     AVIContext *avi = s->priv_data;
     int n, au_byterate, au_ssize, au_scale, nb_frames = 0;
     int64_t file_size;
-    AVCodecContext *stream;
+    AVCodecParameters *par;
 
     file_size = avio_tell(pb);
     for (n = 0; n < s->nb_streams; n++) {
         AVIStream *avist = s->streams[n]->priv_data;
 
         assert(avist->frames_hdr_strm);
-        stream = s->streams[n]->codec;
+        par = s->streams[n]->codecpar;
         avio_seek(pb, avist->frames_hdr_strm, SEEK_SET);
         ff_parse_specific_params(s->streams[n], &au_byterate, &au_ssize, &au_scale);
         if (au_ssize == 0)
             avio_wl32(pb, avist->packet_count);
         else
             avio_wl32(pb, avist->audio_strm_length / au_ssize);
-        if (stream->codec_type == AVMEDIA_TYPE_VIDEO)
+        if (par->codec_type == AVMEDIA_TYPE_VIDEO)
             nb_frames = FFMAX(nb_frames, avist->packet_count);
     }
     if (riff_id == 1) {
@@ -143,7 +143,7 @@ static int avi_write_header(AVFormatContext *s)
     AVIContext *avi = s->priv_data;
     AVIOContext *pb = s->pb;
     int bitrate, n, i, nb_frames, au_byterate, au_ssize, au_scale;
-    AVCodecContext *video_enc;
+    AVCodecParameters *video_par;
     AVStream *video_st = NULL;
     int64_t list1, list2, strh, strf;
     AVDictionaryEntry *t = NULL;
@@ -169,12 +169,12 @@ static int avi_write_header(AVFormatContext *s)
     avio_wl32(pb, 14 * 4);
     bitrate = 0;
 
-    video_enc = NULL;
+    video_par = NULL;
     for (n = 0; n < s->nb_streams; n++) {
-        AVCodecContext *codec = s->streams[n]->codec;
-        bitrate += codec->bit_rate;
-        if (codec->codec_type == AVMEDIA_TYPE_VIDEO) {
-            video_enc = codec;
+        AVCodecParameters *par = s->streams[n]->codecpar;
+        bitrate += par->bit_rate;
+        if (par->codec_type == AVMEDIA_TYPE_VIDEO) {
+            video_par = par;
             video_st = s->streams[n];
         }
     }
@@ -198,9 +198,9 @@ static int avi_write_header(AVFormatContext *s)
     avio_wl32(pb, 0); /* initial frame */
     avio_wl32(pb, s->nb_streams); /* nb streams */
     avio_wl32(pb, 1024 * 1024); /* suggested buffer size */
-    if (video_enc) {
-        avio_wl32(pb, video_enc->width);
-        avio_wl32(pb, video_enc->height);
+    if (video_par) {
+        avio_wl32(pb, video_par->width);
+        avio_wl32(pb, video_par->height);
     } else {
         avio_wl32(pb, 0);
         avio_wl32(pb, 0);
@@ -213,18 +213,18 @@ static int avi_write_header(AVFormatContext *s)
     /* stream list */
     for (i = 0; i < n; i++) {
         AVStream *st = s->streams[i];
-        AVCodecContext *enc = st->codec;
+        AVCodecParameters *par = st->codecpar;
         AVIStream *avist = st->priv_data;
         list2 = ff_start_tag(pb, "LIST");
         ffio_wfourcc(pb, "strl");
 
         /* stream generic header */
         strh = ff_start_tag(pb, "strh");
-        switch (enc->codec_type) {
+        switch (par->codec_type) {
         case AVMEDIA_TYPE_SUBTITLE:
             // XSUB subtitles behave like video tracks, other subtitles
             // are not (yet) supported.
-            if (enc->codec_id != AV_CODEC_ID_XSUB) {
+            if (par->codec_id != AV_CODEC_ID_XSUB) {
                 av_log(s, AV_LOG_ERROR,
                        "Subtitle streams other than DivX XSUB are not supported by the AVI muxer.\n");
                 return AVERROR_PATCHWELCOME;
@@ -242,9 +242,9 @@ static int avi_write_header(AVFormatContext *s)
             ffio_wfourcc(pb, "dats");
             break;
         }
-        if (enc->codec_type == AVMEDIA_TYPE_VIDEO ||
-            enc->codec_id == AV_CODEC_ID_XSUB)
-            avio_wl32(pb, enc->codec_tag);
+        if (par->codec_type == AVMEDIA_TYPE_VIDEO ||
+            par->codec_id == AV_CODEC_ID_XSUB)
+            avio_wl32(pb, par->codec_tag);
         else
             avio_wl32(pb, 1);
         avio_wl32(pb, 0); /* flags */
@@ -268,32 +268,32 @@ static int avi_write_header(AVFormatContext *s)
             avio_wl32(pb, 0);  /* length, XXX: filled later */
 
         /* suggested buffer size */ //FIXME set at the end to largest chunk
-        if (enc->codec_type == AVMEDIA_TYPE_VIDEO)
+        if (par->codec_type == AVMEDIA_TYPE_VIDEO)
             avio_wl32(pb, 1024 * 1024);
-        else if (enc->codec_type == AVMEDIA_TYPE_AUDIO)
+        else if (par->codec_type == AVMEDIA_TYPE_AUDIO)
             avio_wl32(pb, 12 * 1024);
         else
             avio_wl32(pb, 0);
         avio_wl32(pb, -1); /* quality */
         avio_wl32(pb, au_ssize); /* sample size */
         avio_wl32(pb, 0);
-        avio_wl16(pb, enc->width);
-        avio_wl16(pb, enc->height);
+        avio_wl16(pb, par->width);
+        avio_wl16(pb, par->height);
         ff_end_tag(pb, strh);
 
-        if (enc->codec_type != AVMEDIA_TYPE_DATA) {
+        if (par->codec_type != AVMEDIA_TYPE_DATA) {
             strf = ff_start_tag(pb, "strf");
-            switch (enc->codec_type) {
+            switch (par->codec_type) {
             case AVMEDIA_TYPE_SUBTITLE:
                 /* XSUB subtitles behave like video tracks, other subtitles
                  * are not (yet) supported. */
-                if (enc->codec_id != AV_CODEC_ID_XSUB)
+                if (par->codec_id != AV_CODEC_ID_XSUB)
                     break;
             case AVMEDIA_TYPE_VIDEO:
-                ff_put_bmp_header(pb, enc, ff_codec_bmp_tags, 0);
+                ff_put_bmp_header(pb, par, ff_codec_bmp_tags, 0);
                 break;
             case AVMEDIA_TYPE_AUDIO:
-                if (ff_put_wav_header(pb, enc) < 0)
+                if (ff_put_wav_header(s, pb, par) < 0)
                     return -1;
                 break;
             default:
@@ -320,7 +320,7 @@ static int avi_write_header(AVFormatContext *s)
             avio_w8(pb, 0);     /* bIndexSubType (0 == frame index) */
             avio_w8(pb, 0);     /* bIndexType (0 == AVI_INDEX_OF_INDEXES) */
             avio_wl32(pb, 0);   /* nEntriesInUse (will fill out later on) */
-            ffio_wfourcc(pb, avi_stream2fourcc(tag, i, enc->codec_type));
+            ffio_wfourcc(pb, avi_stream2fourcc(tag, i, par->codec_type));
                                 /* dwChunkId */
             avio_wl64(pb, 0);   /* dwReserved[3] */
             // avio_wl32(pb, 0);   /* Must be 0.    */
@@ -329,13 +329,13 @@ static int avi_write_header(AVFormatContext *s)
             ff_end_tag(pb, avist->indexes.indx_start);
         }
 
-        if (enc->codec_type == AVMEDIA_TYPE_VIDEO   &&
+        if (par->codec_type == AVMEDIA_TYPE_VIDEO   &&
             st->sample_aspect_ratio.num > 0 &&
             st->sample_aspect_ratio.den > 0) {
             int vprp       = ff_start_tag(pb, "vprp");
             AVRational dar = av_mul_q(st->sample_aspect_ratio,
-                                      (AVRational) { enc->width,
-                                                     enc->height });
+                                      (AVRational) { par->width,
+                                                     par->height });
             int num, den;
             av_reduce(&num, &den, dar.num, dar.den, 0xFFFF);
 
@@ -343,18 +343,18 @@ static int avi_write_header(AVFormatContext *s)
             avio_wl32(pb, 0); // video standard = unknown
             // TODO: should be avg_frame_rate
             avio_wl32(pb, lrintf(1.0 / av_q2d(st->time_base)));
-            avio_wl32(pb, enc->width);
-            avio_wl32(pb, enc->height);
+            avio_wl32(pb, par->width);
+            avio_wl32(pb, par->height);
             avio_wl16(pb, den);
             avio_wl16(pb, num);
-            avio_wl32(pb, enc->width);
-            avio_wl32(pb, enc->height);
+            avio_wl32(pb, par->width);
+            avio_wl32(pb, par->height);
             avio_wl32(pb, 1); // progressive FIXME
 
-            avio_wl32(pb, enc->height);
-            avio_wl32(pb, enc->width);
-            avio_wl32(pb, enc->height);
-            avio_wl32(pb, enc->width);
+            avio_wl32(pb, par->height);
+            avio_wl32(pb, par->width);
+            avio_wl32(pb, par->height);
+            avio_wl32(pb, par->width);
             avio_wl32(pb, 0);
             avio_wl32(pb, 0);
 
@@ -412,7 +412,7 @@ static int avi_write_ix(AVFormatContext *s)
         AVIStream *avist = s->streams[i]->priv_data;
         int64_t ix, pos;
 
-        avi_stream2fourcc(tag, i, s->streams[i]->codec->codec_type);
+        avi_stream2fourcc(tag, i, s->streams[i]->codecpar->codec_type);
         ix_tag[3] = '0' + i;
 
         /* Writing AVI OpenDML leaf index chunk */
@@ -489,7 +489,7 @@ static int avi_write_idx1(AVFormatContext *s)
             if (!empty) {
                 avist = s->streams[stream_id]->priv_data;
                 avi_stream2fourcc(tag, stream_id,
-                                  s->streams[stream_id]->codec->codec_type);
+                                  s->streams[stream_id]->codecpar->codec_type);
                 ffio_wfourcc(pb, tag);
                 avio_wl32(pb, ie->flags);
                 avio_wl32(pb, ie->pos);
@@ -513,9 +513,9 @@ static int avi_write_packet(AVFormatContext *s, AVPacket *pkt)
     AVIContext *avi     = s->priv_data;
     AVIOContext *pb     = s->pb;
     AVIStream *avist    = s->streams[stream_index]->priv_data;
-    AVCodecContext *enc = s->streams[stream_index]->codec;
+    AVCodecParameters *par = s->streams[stream_index]->codecpar;
 
-    while (enc->block_align == 0 && pkt->dts != AV_NOPTS_VALUE &&
+    while (par->block_align == 0 && pkt->dts != AV_NOPTS_VALUE &&
            pkt->dts > avist->packet_count) {
         AVPacket empty_packet;
 
@@ -540,10 +540,10 @@ static int avi_write_packet(AVFormatContext *s, AVPacket *pkt)
         avi->movi_list = avi_start_new_riff(s, pb, "AVIX", "movi");
     }
 
-    avi_stream2fourcc(tag, stream_index, enc->codec_type);
+    avi_stream2fourcc(tag, stream_index, par->codec_type);
     if (pkt->flags & AV_PKT_FLAG_KEY)
         flags = 0x10;
-    if (enc->codec_type == AVMEDIA_TYPE_AUDIO)
+    if (par->codec_type == AVMEDIA_TYPE_AUDIO)
         avist->audio_strm_length += size;
 
     if (s->pb->seekable) {
@@ -604,15 +604,15 @@ static int avi_write_trailer(AVFormatContext *s)
             avio_skip(pb, 16);
 
             for (n = nb_frames = 0; n < s->nb_streams; n++) {
-                AVCodecContext *stream = s->streams[n]->codec;
+                AVCodecParameters *par = s->streams[n]->codecpar;
                 AVIStream *avist       = s->streams[n]->priv_data;
 
-                if (stream->codec_type == AVMEDIA_TYPE_VIDEO) {
+                if (par->codec_type == AVMEDIA_TYPE_VIDEO) {
                     if (nb_frames < avist->packet_count)
                         nb_frames = avist->packet_count;
                 } else {
-                    if (stream->codec_id == AV_CODEC_ID_MP2 ||
-                        stream->codec_id == AV_CODEC_ID_MP3)
+                    if (par->codec_id == AV_CODEC_ID_MP2 ||
+                        par->codec_id == AV_CODEC_ID_MP3)
                         nb_frames += avist->packet_count;
                 }
             }