avcodec/wavarc: fix 8bit decoding

libavcodec/wavarc.c

@@ -68,9 +68,9 @@ static av_cold int wavarc_init(AVCodecContext *avctx)
     av_channel_layout_default(&avctx->ch_layout, AV_RL16(avctx->extradata + 38));
     avctx->sample_rate = AV_RL32(avctx->extradata + 40);
 
-    switch (avctx->extradata[36]) {
-    case 0: avctx->sample_fmt = AV_SAMPLE_FMT_U8P;  break;
-    case 1: avctx->sample_fmt = AV_SAMPLE_FMT_S16P; break;
+    switch (AV_RL16(avctx->extradata + 38)) {
+    case 1: avctx->sample_fmt = AV_SAMPLE_FMT_U8P;  break;
+    case 2: avctx->sample_fmt = AV_SAMPLE_FMT_S16P; break;
     }
 
     s->shift = 0;
@@ -411,7 +411,7 @@ fail:
             const int *src = s->samples[ch] + s->offset;
 
             for (int n = 0; n < frame->nb_samples; n++)
-                dst[n] = src[n] * (1 << s->shift);
+                dst[n] = src[n] * (1 << s->shift) + 0x80U;
         }
         break;
     case AV_SAMPLE_FMT_S16P:

libavformat/wavarc.c

@@ -89,7 +89,7 @@ static int wavarc_read_header(AVFormatContext *s)
         id = avio_rl32(pb);
         if (id != MKTAG('d','a','t','a'))
             avio_skip(pb, avio_rl32(pb));
-    } while (id != MKTAG('d','a','t','a'));
+    } while (id != MKTAG('d','a','t','a') && !avio_feof(pb));
     avio_skip(pb, 4);
 
     if (AV_RL32(par->extradata + 16) != MKTAG('R','I','F','F'))
@@ -104,11 +104,6 @@ static int wavarc_read_header(AVFormatContext *s)
     avpriv_set_pts_info(st, 64, 1, par->sample_rate);
     st->start_time = 0;
 
-    switch (par->extradata[36]) {
-    case 0: par->format = AV_SAMPLE_FMT_U8P;  break;
-    case 1: par->format = AV_SAMPLE_FMT_S16P; break;
-    }
-
     return 0;
 }