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, 66 insertions, 65 deletions

diff --git a/libavformat/riffenc.c b/libavformat/riffenc.c
index 2e4b7e0b18..e6b8411529 100644
--- a/libavformat/riffenc.c
+++ b/libavformat/riffenc.c
@@ -47,7 +47,8 @@ void ff_end_tag(AVIOContext *pb, int64_t start)
 
 /* WAVEFORMATEX header */
 /* returns the size or -1 on error */
-int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc)
+int ff_put_wav_header(AVFormatContext *s, AVIOContext *pb,
+                      AVCodecParameters *par)
 {
     int bps, blkalign, bytespersec, frame_size;
     int hdrsize = 18;
@@ -56,82 +57,82 @@ int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc)
     uint8_t *riff_extradata       = temp;
     uint8_t *riff_extradata_start = temp;
 
-    if (!enc->codec_tag || enc->codec_tag > 0xffff)
+    if (!par->codec_tag || par->codec_tag > 0xffff)
         return -1;
 
     /* We use the known constant frame size for the codec if known, otherwise
      * fall back on using AVCodecContext.frame_size, which is not as reliable
      * for indicating packet duration. */
-    frame_size = av_get_audio_frame_duration(enc, enc->block_align);
+    frame_size = av_get_audio_frame_duration2(par, par->block_align);
 
-    waveformatextensible = (enc->channels > 2 && enc->channel_layout) ||
-                           enc->sample_rate > 48000 ||
-                           av_get_bits_per_sample(enc->codec_id) > 16;
+    waveformatextensible = (par->channels > 2 && par->channel_layout) ||
+                           par->sample_rate > 48000 ||
+                           av_get_bits_per_sample(par->codec_id) > 16;
 
     if (waveformatextensible)
         avio_wl16(pb, 0xfffe);
     else
-        avio_wl16(pb, enc->codec_tag);
+        avio_wl16(pb, par->codec_tag);
 
-    avio_wl16(pb, enc->channels);
-    avio_wl32(pb, enc->sample_rate);
-    if (enc->codec_id == AV_CODEC_ID_MP2 ||
-        enc->codec_id == AV_CODEC_ID_MP3 ||
-        enc->codec_id == AV_CODEC_ID_GSM_MS) {
+    avio_wl16(pb, par->channels);
+    avio_wl32(pb, par->sample_rate);
+    if (par->codec_id == AV_CODEC_ID_MP2 ||
+        par->codec_id == AV_CODEC_ID_MP3 ||
+        par->codec_id == AV_CODEC_ID_GSM_MS) {
         bps = 0;
     } else {
-        if (!(bps = av_get_bits_per_sample(enc->codec_id))) {
-            if (enc->bits_per_coded_sample)
-                bps = enc->bits_per_coded_sample;
+        if (!(bps = av_get_bits_per_sample(par->codec_id))) {
+            if (par->bits_per_coded_sample)
+                bps = par->bits_per_coded_sample;
             else
                 bps = 16;  // default to 16
         }
     }
-    if (bps != enc->bits_per_coded_sample && enc->bits_per_coded_sample) {
-        av_log(enc, AV_LOG_WARNING,
+    if (bps != par->bits_per_coded_sample && par->bits_per_coded_sample) {
+        av_log(s, AV_LOG_WARNING,
                "requested bits_per_coded_sample (%d) "
                "and actually stored (%d) differ\n",
-               enc->bits_per_coded_sample, bps);
+               par->bits_per_coded_sample, bps);
     }
 
-    if (enc->codec_id == AV_CODEC_ID_MP2) {
+    if (par->codec_id == AV_CODEC_ID_MP2) {
         blkalign = frame_size;
-    } else if (enc->codec_id == AV_CODEC_ID_MP3) {
-        blkalign = 576 * (enc->sample_rate <= 24000 ? 1 : 2);
-    } else if (enc->codec_id == AV_CODEC_ID_AC3) {
+    } else if (par->codec_id == AV_CODEC_ID_MP3) {
+        blkalign = 576 * (par->sample_rate <= 24000 ? 1 : 2);
+    } else if (par->codec_id == AV_CODEC_ID_AC3) {
         blkalign = 3840;                /* maximum bytes per frame */
-    } else if (enc->block_align != 0) { /* specified by the codec */
-        blkalign = enc->block_align;
+    } else if (par->block_align != 0) { /* specified by the codec */
+        blkalign = par->block_align;
     } else
-        blkalign = bps * enc->channels / av_gcd(8, bps);
-    if (enc->codec_id == AV_CODEC_ID_PCM_U8 ||
-        enc->codec_id == AV_CODEC_ID_PCM_S24LE ||
-        enc->codec_id == AV_CODEC_ID_PCM_S32LE ||
-        enc->codec_id == AV_CODEC_ID_PCM_F32LE ||
-        enc->codec_id == AV_CODEC_ID_PCM_F64LE ||
-        enc->codec_id == AV_CODEC_ID_PCM_S16LE) {
-        bytespersec = enc->sample_rate * blkalign;
+        blkalign = bps * par->channels / av_gcd(8, bps);
+    if (par->codec_id == AV_CODEC_ID_PCM_U8 ||
+        par->codec_id == AV_CODEC_ID_PCM_S24LE ||
+        par->codec_id == AV_CODEC_ID_PCM_S32LE ||
+        par->codec_id == AV_CODEC_ID_PCM_F32LE ||
+        par->codec_id == AV_CODEC_ID_PCM_F64LE ||
+        par->codec_id == AV_CODEC_ID_PCM_S16LE) {
+        bytespersec = par->sample_rate * blkalign;
     } else {
-        bytespersec = enc->bit_rate / 8;
+        bytespersec = par->bit_rate / 8;
     }
     avio_wl32(pb, bytespersec); /* bytes per second */
     avio_wl16(pb, blkalign);    /* block align */
     avio_wl16(pb, bps);         /* bits per sample */
-    if (enc->codec_id == AV_CODEC_ID_MP3) {
+    if (par->codec_id == AV_CODEC_ID_MP3) {
         hdrsize += 12;
         bytestream_put_le16(&riff_extradata, 1);    /* wID */
         bytestream_put_le32(&riff_extradata, 2);    /* fdwFlags */
         bytestream_put_le16(&riff_extradata, 1152); /* nBlockSize */
         bytestream_put_le16(&riff_extradata, 1);    /* nFramesPerBlock */
         bytestream_put_le16(&riff_extradata, 1393); /* nCodecDelay */
-    } else if (enc->codec_id == AV_CODEC_ID_MP2) {
+    } else if (par->codec_id == AV_CODEC_ID_MP2) {
         hdrsize += 22;
         /* fwHeadLayer */
         bytestream_put_le16(&riff_extradata, 2);
         /* dwHeadBitrate */
-        bytestream_put_le32(&riff_extradata, enc->bit_rate);
+        bytestream_put_le32(&riff_extradata, par->bit_rate);
         /* fwHeadMode */
-        bytestream_put_le16(&riff_extradata, enc->channels == 2 ? 1 : 8);
+        bytestream_put_le16(&riff_extradata, par->channels == 2 ? 1 : 8);
         /* fwHeadModeExt */
         bytestream_put_le16(&riff_extradata, 0);
         /* wHeadEmphasis */
@@ -142,15 +143,15 @@ int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc)
         bytestream_put_le32(&riff_extradata, 0);
         /* dwPTSHigh */
         bytestream_put_le32(&riff_extradata, 0);
-    } else if (enc->codec_id == AV_CODEC_ID_GSM_MS ||
-               enc->codec_id == AV_CODEC_ID_ADPCM_IMA_WAV) {
+    } else if (par->codec_id == AV_CODEC_ID_GSM_MS ||
+               par->codec_id == AV_CODEC_ID_ADPCM_IMA_WAV) {
         hdrsize += 2;
         /* wSamplesPerBlock */
         bytestream_put_le16(&riff_extradata, frame_size);
-    } else if (enc->extradata_size) {
-        riff_extradata_start = enc->extradata;
-        riff_extradata       = enc->extradata + enc->extradata_size;
-        hdrsize             += enc->extradata_size;
+    } else if (par->extradata_size) {
+        riff_extradata_start = par->extradata;
+        riff_extradata       = par->extradata + par->extradata_size;
+        hdrsize             += par->extradata_size;
     }
     /* write WAVEFORMATEXTENSIBLE extensions */
     if (waveformatextensible) {
@@ -160,9 +161,9 @@ int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc)
         /* ValidBitsPerSample || SamplesPerBlock || Reserved */
         avio_wl16(pb, bps);
         /* dwChannelMask */
-        avio_wl32(pb, enc->channel_layout);
+        avio_wl32(pb, par->channel_layout);
         /* GUID + next 3 */
-        avio_wl32(pb, enc->codec_tag);
+        avio_wl32(pb, par->codec_tag);
         avio_wl32(pb, 0x00100000);
         avio_wl32(pb, 0xAA000080);
         avio_wl32(pb, 0x719B3800);
@@ -179,54 +180,54 @@ int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc)
 }
 
 /* BITMAPINFOHEADER header */
-void ff_put_bmp_header(AVIOContext *pb, AVCodecContext *enc,
+void ff_put_bmp_header(AVIOContext *pb, AVCodecParameters *par,
                        const AVCodecTag *tags, int for_asf)
 {
     /* size */
-    avio_wl32(pb, 40 + enc->extradata_size);
-    avio_wl32(pb, enc->width);
+    avio_wl32(pb, 40 + par->extradata_size);
+    avio_wl32(pb, par->width);
     //We always store RGB TopDown
-    avio_wl32(pb, enc->codec_tag ? enc->height : -enc->height);
+    avio_wl32(pb, par->codec_tag ? par->height : -par->height);
     /* planes */
     avio_wl16(pb, 1);
     /* depth */
-    avio_wl16(pb, enc->bits_per_coded_sample ? enc->bits_per_coded_sample : 24);
+    avio_wl16(pb, par->bits_per_coded_sample ? par->bits_per_coded_sample : 24);
     /* compression type */
-    avio_wl32(pb, enc->codec_tag);
-    avio_wl32(pb, enc->width * enc->height * 3);
+    avio_wl32(pb, par->codec_tag);
+    avio_wl32(pb, par->width * par->height * 3);
     avio_wl32(pb, 0);
     avio_wl32(pb, 0);
     avio_wl32(pb, 0);
     avio_wl32(pb, 0);
 
-    avio_write(pb, enc->extradata, enc->extradata_size);
+    avio_write(pb, par->extradata, par->extradata_size);
 
-    if (!for_asf && enc->extradata_size & 1)
+    if (!for_asf && par->extradata_size & 1)
         avio_w8(pb, 0);
 }
 
 void ff_parse_specific_params(AVStream *st, int *au_rate,
                               int *au_ssize, int *au_scale)
 {
-    AVCodecContext *codec = st->codec;
+    AVCodecParameters *par = st->codecpar;
     int gcd;
     int audio_frame_size;
 
-    audio_frame_size = av_get_audio_frame_duration(codec, 0);
+    audio_frame_size = av_get_audio_frame_duration2(par, 0);
 
-    *au_ssize = codec->block_align;
-    if (audio_frame_size && codec->sample_rate) {
+    *au_ssize = par->block_align;
+    if (audio_frame_size && par->sample_rate) {
         *au_scale = audio_frame_size;
-        *au_rate  = codec->sample_rate;
-    } else if (codec->codec_type == AVMEDIA_TYPE_VIDEO ||
-               codec->codec_type == AVMEDIA_TYPE_DATA ||
-               codec->codec_type == AVMEDIA_TYPE_SUBTITLE) {
+        *au_rate  = par->sample_rate;
+    } else if (par->codec_type == AVMEDIA_TYPE_VIDEO ||
+               par->codec_type == AVMEDIA_TYPE_DATA ||
+               par->codec_type == AVMEDIA_TYPE_SUBTITLE) {
         *au_scale = st->time_base.num;
         *au_rate  = st->time_base.den;
     } else {
-        *au_scale = codec->block_align ? codec->block_align * 8 : 8;
-        *au_rate  = codec->bit_rate ? codec->bit_rate :
-                    8 * codec->sample_rate;
+        *au_scale = par->block_align ? par->block_align * 8 : 8;
+        *au_rate  = par->bit_rate ? par->bit_rate :
+                    8 * par->sample_rate;
     }
     gcd        = av_gcd(*au_scale, *au_rate);
     *au_scale /= gcd;