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, 30 insertions, 30 deletions

diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index 8c75d189b0..9c7e23aa8e 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -105,19 +105,19 @@ static int dash_write(void *opaque, uint8_t *buf, int buf_size)
 }
 
 // RFC 6381
-static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
+static void set_codec_str(AVFormatContext *s, AVCodecParameters *par,
                           char *str, int size)
 {
     const AVCodecTag *tags[2] = { NULL, NULL };
     uint32_t tag;
-    if (codec->codec_type == AVMEDIA_TYPE_VIDEO)
+    if (par->codec_type == AVMEDIA_TYPE_VIDEO)
         tags[0] = ff_codec_movvideo_tags;
-    else if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
+    else if (par->codec_type == AVMEDIA_TYPE_AUDIO)
         tags[0] = ff_codec_movaudio_tags;
     else
         return;
 
-    tag = av_codec_get_tag(tags, codec->codec_id);
+    tag = av_codec_get_tag(tags, par->codec_id);
     if (!tag)
         return;
     if (size < 5)
@@ -128,17 +128,17 @@ static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
     if (!strcmp(str, "mp4a") || !strcmp(str, "mp4v")) {
         uint32_t oti;
         tags[0] = ff_mp4_obj_type;
-        oti = av_codec_get_tag(tags, codec->codec_id);
+        oti = av_codec_get_tag(tags, par->codec_id);
         if (oti)
             av_strlcatf(str, size, ".%02x", oti);
         else
             return;
 
         if (tag == MKTAG('m', 'p', '4', 'a')) {
-            if (codec->extradata_size >= 2) {
-                int aot = codec->extradata[0] >> 3;
+            if (par->extradata_size >= 2) {
+                int aot = par->extradata[0] >> 3;
                 if (aot == 31)
-                    aot = ((AV_RB16(codec->extradata) >> 5) & 0x3f) + 32;
+                    aot = ((AV_RB16(par->extradata) >> 5) & 0x3f) + 32;
                 av_strlcatf(str, size, ".%d", aot);
             }
         } else if (tag == MKTAG('m', 'p', '4', 'v')) {
@@ -147,8 +147,8 @@ static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
         }
     } else if (!strcmp(str, "avc1")) {
         uint8_t *tmpbuf = NULL;
-        uint8_t *extradata = codec->extradata;
-        int extradata_size = codec->extradata_size;
+        uint8_t *extradata = par->extradata;
+        int extradata_size = par->extradata_size;
         if (!extradata_size)
             return;
         if (extradata[0] != 1) {
@@ -506,9 +506,9 @@ static int write_manifest(AVFormatContext *s, int final)
         for (i = 0; i < s->nb_streams; i++) {
             AVStream *st = s->streams[i];
             OutputStream *os = &c->streams[i];
-            if (st->codec->codec_type != AVMEDIA_TYPE_VIDEO)
+            if (st->codecpar->codec_type != AVMEDIA_TYPE_VIDEO)
                 continue;
-            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->width, st->codec->height);
+            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codecpar->width, st->codecpar->height);
             output_segment_list(&c->streams[i], out, c);
             avio_printf(out, "\t\t\t</Representation>\n");
         }
@@ -519,10 +519,10 @@ static int write_manifest(AVFormatContext *s, int final)
         for (i = 0; i < s->nb_streams; i++) {
             AVStream *st = s->streams[i];
             OutputStream *os = &c->streams[i];
-            if (st->codec->codec_type != AVMEDIA_TYPE_AUDIO)
+            if (st->codecpar->codec_type != AVMEDIA_TYPE_AUDIO)
                 continue;
-            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->sample_rate);
-            avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
+            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codecpar->sample_rate);
+            avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codecpar->channels);
             output_segment_list(&c->streams[i], out, c);
             avio_printf(out, "\t\t\t</Representation>\n");
         }
@@ -581,7 +581,7 @@ static int dash_write_header(AVFormatContext *s)
         AVDictionary *opts = NULL;
         char filename[1024];
 
-        os->bit_rate = s->streams[i]->codec->bit_rate;
+        os->bit_rate = s->streams[i]->codecpar->bit_rate;
         if (os->bit_rate) {
             snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
                      " bandwidth=\"%d\"", os->bit_rate);
@@ -611,7 +611,7 @@ static int dash_write_header(AVFormatContext *s)
             ret = AVERROR(ENOMEM);
             goto fail;
         }
-        avcodec_copy_context(st->codec, s->streams[i]->codec);
+        avcodec_parameters_copy(st->codecpar, s->streams[i]->codecpar);
         st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
         st->time_base = s->streams[i]->time_base;
         ctx->avoid_negative_ts = s->avoid_negative_ts;
@@ -651,12 +651,12 @@ static int dash_write_header(AVFormatContext *s)
         // already before being handed to this muxer, so we don't have mismatches
         // between the MPD and the actual segments.
         s->avoid_negative_ts = ctx->avoid_negative_ts;
-        if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
+        if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
             c->has_video = 1;
-        else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
+        else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO)
             c->has_audio = 1;
 
-        set_codec_str(s, st->codec, os->codec_str, sizeof(os->codec_str));
+        set_codec_str(s, st->codecpar, os->codec_str, sizeof(os->codec_str));
         os->first_pts = AV_NOPTS_VALUE;
         os->max_pts = AV_NOPTS_VALUE;
         os->last_dts = AV_NOPTS_VALUE;
@@ -745,24 +745,24 @@ static void find_index_range(AVFormatContext *s, const char *full_path,
 }
 
 static int update_stream_extradata(AVFormatContext *s, OutputStream *os,
-                                   AVCodecContext *codec)
+                                   AVCodecParameters *par)
 {
     uint8_t *extradata;
 
-    if (os->ctx->streams[0]->codec->extradata_size || !codec->extradata_size)
+    if (os->ctx->streams[0]->codecpar->extradata_size || !par->extradata_size)
         return 0;
 
-    extradata = av_malloc(codec->extradata_size);
+    extradata = av_malloc(par->extradata_size);
 
     if (!extradata)
         return AVERROR(ENOMEM);
 
-    memcpy(extradata, codec->extradata, codec->extradata_size);
+    memcpy(extradata, par->extradata, par->extradata_size);
 
-    os->ctx->streams[0]->codec->extradata = extradata;
-    os->ctx->streams[0]->codec->extradata_size = codec->extradata_size;
+    os->ctx->streams[0]->codecpar->extradata = extradata;
+    os->ctx->streams[0]->codecpar->extradata_size = par->extradata_size;
 
-    set_codec_str(s, codec, os->codec_str, sizeof(os->codec_str));
+    set_codec_str(s, par, os->codec_str, sizeof(os->codec_str));
 
     return 0;
 }
@@ -788,7 +788,7 @@ static int dash_flush(AVFormatContext *s, int final, int stream)
         // Flush all audio streams as well, in sync with video keyframes,
         // but not the other video streams.
         if (stream >= 0 && i != stream) {
-            if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
+            if (s->streams[i]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO)
                 continue;
             // Make sure we don't flush audio streams multiple times, when
             // all video streams are flushed one at a time.
@@ -867,7 +867,7 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
     int64_t seg_end_duration = (os->segment_index) * (int64_t) c->min_seg_duration;
     int ret;
 
-    ret = update_stream_extradata(s, os, st->codec);
+    ret = update_stream_extradata(s, os, st->codecpar);
     if (ret < 0)
         return ret;
 
@@ -892,7 +892,7 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
     if (os->first_pts == AV_NOPTS_VALUE)
         os->first_pts = pkt->pts;
 
-    if ((!c->has_video || st->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
+    if ((!c->has_video || st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) &&
         pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&
         av_compare_ts(pkt->pts - os->first_pts, st->time_base,
                       seg_end_duration, AV_TIME_BASE_Q) >= 0) {