adxdec: Do not require extradata.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

libavcodec/adxdec.c

@@ -38,16 +38,16 @@ static av_cold int adx_decode_init(AVCodecContext *avctx)
     ADXContext *c = avctx->priv_data;
     int ret, header_size;
 
-    if (avctx->extradata_size < 24)
-        return AVERROR_INVALIDDATA;
-
-    if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,
-                                        avctx->extradata_size, &header_size,
-                                        c->coeff)) < 0) {
-        av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
-        return AVERROR_INVALIDDATA;
+    if (avctx->extradata_size >= 24) {
+        if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,
+                                            avctx->extradata_size, &header_size,
+                                            c->coeff)) < 0) {
+            av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
+            return AVERROR_INVALIDDATA;
+        }
+        c->channels      = avctx->channels;
+        c->header_parsed = 1;
     }
-    c->channels = avctx->channels;
 
     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
 
@@ -107,6 +107,23 @@ static int adx_decode_frame(AVCodecContext *avctx, void *data,
         return buf_size;
     }
 
+    if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {
+        int header_size;
+        if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,
+                                            c->coeff)) < 0) {
+            av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
+            return AVERROR_INVALIDDATA;
+        }
+        c->channels      = avctx->channels;
+        c->header_parsed = 1;
+        if (buf_size < header_size)
+            return AVERROR_INVALIDDATA;
+        buf      += header_size;
+        buf_size -= header_size;
+    }
+    if (!c->header_parsed)
+        return AVERROR_INVALIDDATA;
+
     /* calculate number of blocks in the packet */
     num_blocks = buf_size / (BLOCK_SIZE * c->channels);