1 files changed, 37 insertions, 0 deletions
diff --git a/libavcodec/mpegaudiodecheader.c b/libavcodec/mpegaudiodecheader.c
index a0bd4fcee6..be7abc619d 100644
--- a/libavcodec/mpegaudiodecheader.c
+++ b/libavcodec/mpegaudiodecheader.c
@@ -108,3 +108,40 @@ int ff_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
 #endif
     return 0;
 }
+
+int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate)
+{
+    MPADecodeHeader s1, *s = &s1;
+
+    if (ff_mpa_check_header(head) != 0)
+        return -1;
+
+    if (ff_mpegaudio_decode_header(s, head) != 0) {
+        return -1;
+    }
+
+    switch(s->layer) {
+    case 1:
+        avctx->codec_id = CODEC_ID_MP1;
+        *frame_size = 384;
+        break;
+    case 2:
+        avctx->codec_id = CODEC_ID_MP2;
+        *frame_size = 1152;
+        break;
+    default:
+    case 3:
+        avctx->codec_id = CODEC_ID_MP3;
+        if (s->lsf)
+            *frame_size = 576;
+        else
+            *frame_size = 1152;
+        break;
+    }
+
+    *sample_rate = s->sample_rate;
+    *channels = s->nb_channels;
+    *bit_rate = s->bit_rate;
+    avctx->sub_id = s->layer;
+    return s->frame_size;
+}