fftools/ffmpeg_dec: pass AVCodecParameters through DecoderOpts

Do not retrieve it from InputStream directly.

This is a step towards decoupling Decoder and InputStream.

fftools/ffmpeg.h

@@ -298,6 +298,7 @@ typedef struct DecoderOpts {
     char                       *name;
 
     const AVCodec              *codec;
+    const AVCodecParameters    *par;
 
     /* hwaccel options */
     enum HWAccelID              hwaccel_id;

fftools/ffmpeg_dec.c

@@ -990,13 +990,13 @@ int dec_open(InputStream *ist, Scheduler *sch, unsigned sch_idx,
             return AVERROR(ENOMEM);
     }
 
-    dp->sar_override = ist->par->sample_aspect_ratio;
+    dp->sar_override = o->par->sample_aspect_ratio;
 
     dp->dec_ctx = avcodec_alloc_context3(codec);
     if (!dp->dec_ctx)
         return AVERROR(ENOMEM);
 
-    ret = avcodec_parameters_to_context(dp->dec_ctx, ist->par);
+    ret = avcodec_parameters_to_context(dp->dec_ctx, o->par);
     if (ret < 0) {
         av_log(dp, AV_LOG_ERROR, "Error initializing the decoder context.\n");
         return ret;

fftools/ffmpeg_demux.c

@@ -931,6 +931,7 @@ static int ist_use(InputStream *ist, int decoding_needed)
         ds->dec_opts.name = ds->dec_name;
 
         ds->dec_opts.codec = ist->dec;
+        ds->dec_opts.par   = ist->par;
 
         ret = dec_open(ist, d->sch, ds->sch_idx_dec,
                        &ist->decoder_opts, &ds->dec_opts);