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, 28 insertions, 27 deletions

diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
index 8ef8eebc54..ffbea97633 100644
--- a/libavformat/mpegtsenc.c
+++ b/libavformat/mpegtsenc.c
@@ -252,7 +252,7 @@ static void mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
             err = 1;
             break;
         }
-        switch (st->codec->codec_id) {
+        switch (st->codecpar->codec_id) {
         case AV_CODEC_ID_MPEG1VIDEO:
         case AV_CODEC_ID_MPEG2VIDEO:
             stream_type = STREAM_TYPE_VIDEO_MPEG2;
@@ -299,9 +299,9 @@ static void mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
         q += 2; /* patched after */
 
         /* write optional descriptors here */
-        switch (st->codec->codec_type) {
+        switch (st->codecpar->codec_type) {
         case AVMEDIA_TYPE_AUDIO:
-            if (st->codec->codec_id == AV_CODEC_ID_AC3 && (ts->flags & MPEGTS_FLAG_SYSTEM_B)) {
+            if (st->codecpar->codec_id == AV_CODEC_ID_AC3 && (ts->flags & MPEGTS_FLAG_SYSTEM_B)) {
                 *q++ = 0x6a; /* ETSI EN 300 468 AC-3 descriptor */
                 *q++ = 1;
                 *q++ = 0x00;
@@ -361,8 +361,8 @@ static void mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
                 break;
             }
 
-            if (st->codec->extradata_size == 4) {
-                memcpy(q, st->codec->extradata, 4);
+            if (st->codecpar->extradata_size == 4) {
+                memcpy(q, st->codecpar->extradata, 4);
                 q += 4;
             } else {
                 put16(&q, 1);     /* page id */
@@ -607,13 +607,13 @@ static int mpegts_write_header(AVFormatContext *s)
         ts_st->first_pts_check = 1;
         ts_st->cc              = 15;
         /* update PCR pid by using the first video stream */
-        if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
+        if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
             service->pcr_pid == 0x1fff) {
             service->pcr_pid = ts_st->pid;
             pcr_st           = st;
         }
-        if (st->codec->codec_id == AV_CODEC_ID_AAC &&
-            st->codec->extradata_size > 0) {
+        if (st->codecpar->codec_id == AV_CODEC_ID_AAC &&
+            st->codecpar->extradata_size > 0) {
             AVStream *ast;
             ts_st->amux = avformat_alloc_context();
             if (!ts_st->amux) {
@@ -631,7 +631,7 @@ static int mpegts_write_header(AVFormatContext *s)
                 ret = AVERROR(ENOMEM);
                 goto fail;
             }
-            ret = avcodec_copy_context(ast->codec, st->codec);
+            ret = avcodec_parameters_copy(ast->codecpar, st->codecpar);
             if (ret != 0)
                 goto fail;
             ast->time_base = st->time_base;
@@ -664,14 +664,15 @@ static int mpegts_write_header(AVFormatContext *s)
         /* Arbitrary values, PAT/PMT could be written on key frames */
         ts->sdt_packet_period = 200;
         ts->pat_packet_period = 40;
-        if (pcr_st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
-            if (!pcr_st->codec->frame_size) {
+        if (pcr_st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
+            int frame_size = av_get_audio_frame_duration2(pcr_st->codecpar, 0);
+            if (!frame_size) {
                 av_log(s, AV_LOG_WARNING, "frame size not set\n");
                 service->pcr_packet_period =
-                    pcr_st->codec->sample_rate / (10 * 512);
+                    pcr_st->codecpar->sample_rate / (10 * 512);
             } else {
                 service->pcr_packet_period =
-                    pcr_st->codec->sample_rate / (10 * pcr_st->codec->frame_size);
+                    pcr_st->codecpar->sample_rate / (10 * frame_size);
             }
         } else {
             // max delta PCR 0.1s
@@ -926,19 +927,19 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
             *q++ = 0x00;
             *q++ = 0x01;
             private_code = 0;
-            if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
-                if (st->codec->codec_id == AV_CODEC_ID_DIRAC)
+            if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
+                if (st->codecpar->codec_id == AV_CODEC_ID_DIRAC)
                     *q++ = 0xfd;
                 else
                     *q++ = 0xe0;
-            } else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO &&
-                       (st->codec->codec_id == AV_CODEC_ID_MP2 ||
-                        st->codec->codec_id == AV_CODEC_ID_MP3 ||
-                        st->codec->codec_id == AV_CODEC_ID_AAC)) {
+            } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
+                       (st->codecpar->codec_id == AV_CODEC_ID_MP2 ||
+                        st->codecpar->codec_id == AV_CODEC_ID_MP3 ||
+                        st->codecpar->codec_id == AV_CODEC_ID_AAC)) {
                 *q++ = 0xc0;
             } else {
                 *q++ = 0xbd;
-                if (st->codec->codec_type == AVMEDIA_TYPE_SUBTITLE)
+                if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
                     private_code = 0x20;
             }
             header_len = 0;
@@ -951,8 +952,8 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
                 header_len += 5;
                 flags      |= 0x40;
             }
-            if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
-                st->codec->codec_id == AV_CODEC_ID_DIRAC) {
+            if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
+                st->codecpar->codec_id == AV_CODEC_ID_DIRAC) {
                 /* set PES_extension_flag */
                 pes_extension = 1;
                 flags        |= 0x01;
@@ -971,7 +972,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
             *q++ = len;
             val  = 0x80;
             /* data alignment indicator is required for subtitle data */
-            if (st->codec->codec_type == AVMEDIA_TYPE_SUBTITLE)
+            if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
                 val |= 0x04;
             *q++ = val;
             *q++ = flags;
@@ -984,7 +985,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
                 write_pts(q, 1, dts);
                 q += 5;
             }
-            if (pes_extension && st->codec->codec_id == AV_CODEC_ID_DIRAC) {
+            if (pes_extension && st->codecpar->codec_id == AV_CODEC_ID_DIRAC) {
                 flags = 0x01;  /* set PES_extension_flag_2 */
                 *q++  = flags;
                 *q++  = 0x80 | 0x01; /* marker bit + extension length */
@@ -1068,7 +1069,7 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
     }
     ts_st->first_pts_check = 0;
 
-    if (st->codec->codec_id == AV_CODEC_ID_H264) {
+    if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
         const uint8_t *p = buf, *buf_end = p + size;
         uint32_t state = -1;
 
@@ -1095,7 +1096,7 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
             buf     = data;
             size    = pkt->size + 6;
         }
-    } else if (st->codec->codec_id == AV_CODEC_ID_AAC) {
+    } else if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
         if (pkt->size < 2) {
             av_log(s, AV_LOG_ERROR, "AAC packet too short\n");
             return AVERROR_INVALIDDATA;
@@ -1129,7 +1130,7 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
         }
     }
 
-    if (st->codec->codec_type != AVMEDIA_TYPE_AUDIO) {
+    if (st->codecpar->codec_type != AVMEDIA_TYPE_AUDIO) {
         // for video and subtitle, write a single pes packet
         mpegts_write_pes(s, st, buf, size, pts, dts,
                          pkt->flags & AV_PKT_FLAG_KEY);