[Ffmpeg-devel] svn 6835 crash in mpeg12.c

Aaron Williams aaronw
Sun Oct 29 19:38:01 CET 2006

When trying to transcode a mpeg 2 file to h.264 I am immediately getting
a crash. Yesterday's build did  not have this problem.

I'm having trouble debugging this, probably due to the heavy compiler


run -pass 1 -i Battlestar\ Galactica\ -\ Exodus.mpg -vcodec h264 -acodec
ac3 -ab 128 -ac 2 -b 1200k -maxrate 2000k -croptop 60 -cropbottom 60
-cropleft 16 -s 704x360 -y -deinterlace -aspect 16:9 

#0  mpeg_decode_mb (s=0xabed20, block=<value optimized out>) at
#1  0x000000000055a2ff in mpeg_decode_slice (s1=0xabed20, mb_y=<value
optimized out>, buf=0x7fff8bc06760,
    buf_size=<value optimized out>) at mpeg12.c:2591
#2  0x000000000055aee4 in mpeg_decode_frame (avctx=0xabd310,
    data_size=0x7fff8bc06ccc, buf=0xb3d040 "", buf_size=52400) at
#3  0x0000000000473a83 in avcodec_decode_video (avctx=0xabd310,
    got_picture_ptr=0x7fff8bc06ccc, buf=0x0, buf_size=22) at utils.c:901
#4  0x0000000000426454 in av_find_stream_info (ic=0xab4070) at utils.c:1724
#5  0x0000000000419657 in opt_input_file (filename=0x7fff8bc07f40
"Battlestar Galactica - Exodus.mpg")
    at ffmpeg.c:2616
#6  0x00000000004214bc in parse_options (argc=30, argv=0x7fff8bc07628,
options=0x81b5e0) at cmdutils.c:101
#7  0x000000000041f360 in main (argc=30, argv=0x7fff8bc07628) at

mpeg_decode_mb (s=0xabed20, block=<value optimized out>) at mpeg12.c:1916
1916        block[0] = dc << (3 - s->intra_dc_precision);
(gdb) p s
$1 = (MpegEncContext *) 0xabed20
(gdb) p block
$2 = <value optimized out>
(gdb) p dc
No symbol "dc" in current context.
(gdb) p s->intra_dc_precision
$3 = 0
(gdb) p s->block
$5 = (DCTELEM (*)[64]) 0xb1aaf0
(gdb) p s->block[0]
$6 = {0 <repeats 64 times>}

(gdb) p s->pblocks
$7 = {0x0, 0xb1a570, 0xb1a5f0, 0xb1a670, 0xb1a6f0, 0xb1a770, 0xb1a7f0,
0xb1a870, 0xb1a8f0, 0xb1a970,
  0xb1a9f0, 0xb1aa70}

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