lavc: add avcodec_is_open().

It allows to check whether an AVCodecContext is open in a documented
way. Right now the undocumented way this check is done in lavf/lavc is
by checking whether AVCodecContext.codec is NULL. However it's desirable
to be able to set AVCodecContext.codec before avcodec_open2().

1 files changed, 8 insertions, 0 deletions

diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 34a4122..3ee6b09 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -627,6 +627,9 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, AVCodec *codec, AVD
     int ret = 0;
     AVDictionary *tmp = NULL;
 
+    if (avcodec_is_open(avctx))
+        return 0;
+
     if (avctx->extradata_size < 0 || avctx->extradata_size >= FF_MAX_EXTRADATA_SIZE)
         return AVERROR(EINVAL);
 
@@ -1803,3 +1806,8 @@ enum AVMediaType avcodec_get_type(enum CodecID codec_id)
 
     return AVMEDIA_TYPE_UNKNOWN;
 }
+
+int avcodec_is_open(AVCodecContext *s)
+{
+    return !!s->internal;
+}