X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fac3dec.c;h=c7deb56e1c61c5bfe2b98a685cca26c4d393439e;hb=1c7f252783aec37e4ff8049476386f63afe91756;hp=ba731314b4886757883b6124f7be00a42a957d3b;hpb=8e1b5ba53839dca3951f9760b390456436ef96d1;p=ffmpeg

diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index ba731314b48..c7deb56e1c6 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -33,6 +33,7 @@
 #include "libavutil/crc.h"
 #include "libavutil/downmix_info.h"
 #include "libavutil/opt.h"
+#include "libavutil/thread.h"
 #include "bswapdsp.h"
 #include "internal.h"
 #include "aac_ac3_parser.h"
@@ -183,23 +184,26 @@ static av_cold void ac3_tables_init(void)
  */
 static av_cold int ac3_decode_init(AVCodecContext *avctx)
 {
+    static AVOnce init_static_once = AV_ONCE_INIT;
     AC3DecodeContext *s = avctx->priv_data;
-    int i;
+    int i, ret;
 
     s->avctx = avctx;
 
-    ac3_tables_init();
-    ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
-    ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
+    if ((ret = ff_mdct_init(&s->imdct_256, 8, 1, 1.0)) < 0 ||
+        (ret = ff_mdct_init(&s->imdct_512, 9, 1, 1.0)) < 0)
+        return ret;
     AC3_RENAME(ff_kbd_window_init)(s->window, 5.0, 256);
     ff_bswapdsp_init(&s->bdsp);
 
 #if (USE_FIXED)
     s->fdsp = avpriv_alloc_fixed_dsp(avctx->flags & AV_CODEC_FLAG_BITEXACT);
 #else
-    s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
     ff_fmt_convert_init(&s->fmt_conv, avctx);
+    s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
 #endif
+    if (!s->fdsp)
+        return AVERROR(ENOMEM);
 
     ff_ac3dsp_init(&s->ac3dsp, avctx->flags & AV_CODEC_FLAG_BITEXACT);
     av_lfg_init(&s->dith_state, 0);
@@ -223,6 +227,8 @@ static av_cold int ac3_decode_init(AVCodecContext *avctx)
         s->dlyptr[i] = s->delay[i];
     }
 
+    ff_thread_once(&init_static_once, ac3_tables_init);
+
     return 0;
 }
 
@@ -1467,6 +1473,7 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data,
     int buf_size, full_buf_size = avpkt->size;
     AC3DecodeContext *s = avctx->priv_data;
     int blk, ch, err, offset, ret;
+    int i;
     int skip = 0, got_independent_frame = 0;
     const uint8_t *channel_map;
     uint8_t extended_channel_map[EAC3_MAX_CHANNELS];
@@ -1477,14 +1484,23 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data,
     s->superframe_size = 0;
 
     buf_size = full_buf_size;
-    while (buf_size > 2) {
-        if (AV_RB16(buf) != 0x770B && AV_RL16(buf) != 0x770B) {
-            buf += 1;
-            buf_size -= 1;
-            continue;
+    for (i = 1; i < buf_size; i += 2) {
+        if (buf[i] == 0x77 || buf[i] == 0x0B) {
+            if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) {
+                i--;
+                break;
+            } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) {
+                break;
+            }
         }
-        break;
     }
+    if (i >= buf_size)
+        return AVERROR_INVALIDDATA;
+    if (i > 10)
+        return i;
+    buf += i;
+    buf_size -= i;
+
     /* copy input buffer to decoder context to avoid reading past the end
        of the buffer, which can be caused by a damaged input stream. */
     if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {