fftools/ffmpeg: store a separate copy of input codec parameters

Use it instead of AVStream.codecpar in the main thread. While
AVStream.codecpar is documented to only be updated when the stream is
added or avformat_find_stream_info(), it is actually updated during
demuxing. Accessing it from a different thread then constitutes a race.

Ideally, some mechanism should eventually be provided for signalling
parameter updates to the user. Then the demuxing thread could pick up
the changes and propagate them to the decoder.

1 files changed, 6 insertions, 0 deletions

diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 6991ba7632..44cc23fa84 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -323,6 +323,12 @@ typedef struct InputStream {
 #define DECODING_FOR_FILTER 2
     int processing_needed;   /* non zero if the packets must be processed */
 
+    /**
+     * Codec parameters - to be used by the decoding/streamcopy code.
+     * st->codecpar should not be accessed, because it may be modified
+     * concurrently by the demuxing thread.
+     */
+    AVCodecParameters *par;
     AVCodecContext *dec_ctx;
     const AVCodec *dec;
     AVFrame *decoded_frame;