]> git.sesse.net Git - ffmpeg/commitdiff
mpegaudiodec: fix seeking.
authorRonald S. Bultje <rsbultje@gmail.com>
Fri, 30 Dec 2011 21:08:21 +0000 (13:08 -0800)
committerJustin Ruggles <justin.ruggles@gmail.com>
Sat, 31 Dec 2011 19:19:09 +0000 (14:19 -0500)
The safe bitstream reader does not allow using skip_bits_long() to seek to a
point before the start of the buffer, which was needed by the mp3 decoder.
This change instead calculates the start point of the first valid granule and
skips to that position.

Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>
libavcodec/mpegaudiodec.c

index 63ae455199c4ac25ffbecb766b25c213742ad740..ad3b199e24ff22ba188d0dbcc9eb629cad97130b 100644 (file)
@@ -1551,25 +1551,27 @@ static int mp_decode_layer3(MPADecodeContext *s)
 #if !UNCHECKED_BITSTREAM_READER
         s->gb.size_in_bits_plus8 += EXTRABYTES * 8;
 #endif
-        skip_bits_long(&s->gb, 8*(s->last_buf_size - main_data_begin));
-    }
-
-    for (gr = 0; gr < nb_granules; gr++) {
-        for (ch = 0; ch < s->nb_channels; ch++) {
-            g = &s->granules[ch][gr];
-            if (get_bits_count(&s->gb) < 0) {
-                av_log(s->avctx, AV_LOG_DEBUG, "mdb:%d, lastbuf:%d skipping granule %d\n",
-                       main_data_begin, s->last_buf_size, gr);
-                skip_bits_long(&s->gb, g->part2_3_length);
+        s->last_buf_size <<= 3;
+        for (gr = 0, ch = 0; gr < nb_granules && (s->last_buf_size >> 3) < main_data_begin; gr++, ch = 0) {
+            for (; ch < s->nb_channels && (s->last_buf_size >> 3) < main_data_begin; ch++) {
+                g = &s->granules[ch][gr];
+                s->last_buf_size += g->part2_3_length;
                 memset(g->sb_hybrid, 0, sizeof(g->sb_hybrid));
-                if (get_bits_count(&s->gb) >= s->gb.size_in_bits && s->in_gb.buffer) {
-                    skip_bits_long(&s->in_gb, get_bits_count(&s->gb) - s->gb.size_in_bits);
-                    s->gb           = s->in_gb;
-                    s->in_gb.buffer = NULL;
-                }
-                continue;
             }
+        }
+        skip_bits_long(&s->gb, s->last_buf_size - 8 * main_data_begin);
+        if (get_bits_count(&s->gb) >= s->gb.size_in_bits && s->in_gb.buffer) {
+            skip_bits_long(&s->in_gb, get_bits_count(&s->gb) - s->gb.size_in_bits);
+            s->gb           = s->in_gb;
+            s->in_gb.buffer = NULL;
+        }
+    } else {
+        gr = ch = 0;
+    }
 
+    for (; gr < nb_granules; gr++, ch = 0) {
+        for (; ch < s->nb_channels; ch++) {
+            g = &s->granules[ch][gr];
             bits_pos = get_bits_count(&s->gb);
 
             if (!s->lsf) {