rtpdec_xiph: Split packets in the depacketizer

The vorbis decoder doesn't handle more than one audio frame packed into
the same AVPacket, so they need to be split in the depacketizer.

Originally committed as revision 24704 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rtpdec_xiph.c

@@ -43,6 +43,9 @@ struct PayloadContext {
     unsigned ident;             ///< 24-bit stream configuration identifier
     uint32_t timestamp;
     ByteIOContext* fragment;    ///< buffer for split payloads
+    uint8_t *split_buf;
+    int split_pos, split_buf_len, split_buf_size;
+    int split_pkts;
 };
 
 static PayloadContext *xiph_new_context(void)
@@ -63,6 +66,7 @@ static inline void free_fragment_if_needed(PayloadContext * data)
 static void xiph_free_context(PayloadContext * data)
 {
     free_fragment_if_needed(data);
+    av_free(data->split_buf);
     av_free(data);
 }
 
@@ -76,6 +80,29 @@ static int xiph_handle_packet(AVFormatContext * ctx,
 
     int ident, fragmented, tdt, num_pkts, pkt_len;
 
+    if (!buf) {
+        if (!data->split_buf || data->split_pos + 2 > data->split_buf_len ||
+            data->split_pkts <= 0) {
+            av_log(ctx, AV_LOG_ERROR, "No more data to return\n");
+            return AVERROR_INVALIDDATA;
+        }
+        pkt_len = AV_RB16(data->split_buf + data->split_pos);
+        data->split_pos += 2;
+        if (data->split_pos + pkt_len > data->split_buf_len) {
+            av_log(ctx, AV_LOG_ERROR, "Not enough data to return\n");
+            return AVERROR_INVALIDDATA;
+        }
+        if (av_new_packet(pkt, pkt_len)) {
+            av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
+            return AVERROR(ENOMEM);
+        }
+        pkt->stream_index = st->index;
+        memcpy(pkt->data, data->split_buf + data->split_pos, pkt_len);
+        data->split_pos += pkt_len;
+        data->split_pkts--;
+        return data->split_pkts > 0;
+    }
+
     if (len < 6) {
         av_log(ctx, AV_LOG_ERROR, "Invalid %d byte packet\n", len);
         return AVERROR_INVALIDDATA;
@@ -112,41 +139,33 @@ static int xiph_handle_packet(AVFormatContext * ctx,
     len -= 6;
 
     if (fragmented == 0) {
-        // whole frame(s)
-        int i, data_len, write_len;
-        buf -= 2;
-        len += 2;
-
-        // fast first pass to calculate total length
-        for (i = 0, data_len = 0;  (i < num_pkts) && (len >= 2);  i++) {
-            int off   = data_len + (i << 1);
-            pkt_len   = AV_RB16(buf + off);
-            data_len += pkt_len;
-            len      -= pkt_len + 2;
-        }
-
-        if (len < 0 || i < num_pkts) {
-            av_log(ctx, AV_LOG_ERROR,
-                   "Bad packet: %d bytes left at frame %d of %d\n",
-                   len, i, num_pkts);
-            return AVERROR_INVALIDDATA;
-        }
-
-        if (av_new_packet(pkt, data_len)) {
+        if (av_new_packet(pkt, pkt_len)) {
             av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
             return AVERROR(ENOMEM);
         }
         pkt->stream_index = st->index;
-
-        // concatenate frames
-        for (i = 0, write_len = 0; write_len < data_len; i++) {
-            pkt_len = AV_RB16(buf);
-            buf += 2;
-            memcpy(pkt->data + write_len, buf, pkt_len);
-            write_len += pkt_len;
+        memcpy(pkt->data, buf, pkt_len);
         buf += pkt_len;
+        len -= pkt_len;
+        num_pkts--;
+
+        if (num_pkts > 0) {
+            if (len > data->split_buf_size || !data->split_buf) {
+                av_freep(&data->split_buf);
+                data->split_buf_size = 2 * len;
+                data->split_buf = av_malloc(data->split_buf_size);
+                if (!data->split_buf) {
+                    av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
+                    av_free_packet(pkt);
+                    return AVERROR(ENOMEM);
+                }
+            }
+            memcpy(data->split_buf, buf, len);
+            data->split_buf_len = len;
+            data->split_pos = 0;
+            data->split_pkts = num_pkts;
+            return 1;
         }
-        assert(write_len == data_len);
 
         return 0;