[libav-devel] [PATCH 3/3] lavc: set AVCodecContext.codec in avcodec_get_context_defaults3().

[Anton Khirnov]

This way, if the AVCodecContext is allocated for a specific codec, the
caller doesn't need to store this codec separately and then pass it
again to avcodec_open2().

It also allows to set codec private options using av_opt_set_* before
opening the codec.
---
 libavcodec/avcodec.h |    5 +++++
 libavcodec/options.c |    1 +
 libavcodec/utils.c   |   11 ++++++-----
 libavformat/utils.c  |    8 +++++---
 4 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 1928ca6..b82be0c 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -3518,6 +3518,11 @@ int avcodec_default_execute2(AVCodecContext *c, int 
(*func)(AVCodecContext *c2,
  * @endcode
  *
  * @param avctx The context to initialize.
+ * @param codec The codec to open this context for. If a non-NULL codec has 
been
+ *              previously passed to avcodec_alloc_context3() or
+ *              avcodec_get_context_defaults3() for this context, then this
+ *              parameter MUST be either NULL or equal to the previously passed
+ *              codec.
  * @param options A dictionary filled with AVCodecContext and codec-private 
options.
  *                On return this object will be filled with options that were 
not found.
  *
diff --git a/libavcodec/options.c b/libavcodec/options.c
index 52fc664..eb80375 100644
--- a/libavcodec/options.c
+++ b/libavcodec/options.c
@@ -432,6 +432,7 @@ int avcodec_get_context_defaults3(AVCodecContext *s, 
AVCodec *codec){
     s->av_class = &av_codec_context_class;
 
     s->codec_type = codec ? codec->type : AVMEDIA_TYPE_UNKNOWN;
+    s->codec      = codec;
     av_opt_set_defaults(s);
 
     s->time_base           = (AVRational){0,1};
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 9cdae22..0c48390 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -630,6 +630,12 @@ int attribute_align_arg avcodec_open2(AVCodecContext 
*avctx, AVCodec *codec, AVD
     if (avcodec_is_open(avctx))
         return 0;
 
+    if ((!codec && !avctx->codec) ||
+        (codec && avctx->codec && codec != avctx->codec))
+        return AVERROR(EINVAL);
+    if (!codec)
+        codec = avctx->codec;
+
     if (avctx->extradata_size < 0 || avctx->extradata_size >= 
FF_MAX_EXTRADATA_SIZE)
         return AVERROR(EINVAL);
 
@@ -649,11 +655,6 @@ int attribute_align_arg avcodec_open2(AVCodecContext 
*avctx, AVCodec *codec, AVD
         goto end;
     }
 
-    if(avctx->codec || !codec) {
-        ret = AVERROR(EINVAL);
-        goto end;
-    }
-
     avctx->internal = av_mallocz(sizeof(AVCodecInternal));
     if (!avctx->internal) {
         ret = AVERROR(ENOMEM);
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 017d1e0..2850a14 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -2009,7 +2009,9 @@ static int try_decode_frame(AVStream *st, AVPacket 
*avpkt, AVDictionary **option
     if (!avcodec_is_open(st->codec)) {
         AVDictionary *thread_opt = NULL;
 
-        codec = avcodec_find_decoder(st->codec->codec_id);
+        codec = st->codec->codec ? st->codec->codec :
+                                   avcodec_find_decoder(st->codec->codec_id);
+
         if (!codec)
             return -1;
 
@@ -2169,8 +2171,8 @@ int avformat_find_stream_info(AVFormatContext *ic, 
AVDictionary **options)
                 st->parser->flags |= PARSER_FLAG_COMPLETE_FRAMES;
             }
         }
-        assert(!st->codec->codec);
-        codec = avcodec_find_decoder(st->codec->codec_id);
+        codec = st->codec->codec ? st->codec->codec :
+                                   avcodec_find_decoder(st->codec->codec_id);
 
         /* force thread count to 1 since the h264 decoder will not extract SPS
          *  and PPS to extradata during multi-threaded decoding */
-- 
1.7.7.3

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