[Ffmpeg-devel] Re: [PATCH] Tiertex .SEQ files support

Baptiste Coudurier baptiste.coudurier
Wed Oct 11 20:01:55 CEST 2006


Hi

Michael Niedermayer wrote:
>>>> [...]
>>>>
>>>> Am I missing something ?
>>> the few url_fseek() will likely be faster then the memcpy(), benchmarks
>>> are of course welcome ...
>> Well, there is no real need to do benchmarks. If you don't read the
>> whole 6kb frame buffer at once, you'll need to do at most 6 reads by
>> frame (1 for palette data, 1 for audio and 4 for video) and do the
>> appropriate seeking before each read. Thus, number of I/O will be much
>> more important.
> 
> libavformat uses an internal buffer (see aviobuf.c) so there should be no
> additional external I/O
> 
> [...]
> 
> patch looks ok
> 

While testing it, I experienced SIGSEGV:

ffmpeg -i Gameover.seq test.mpg

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1480051008 (LWP 24653)]
0x083c54a7 in seqvideo_decode_frame (avctx=0x8667180, data=0xafc43f04,
data_size=0xafc44090, buf=0x86eadd0 "\003",
    buf_size=8210) at tiertexseqv.c:131
131             dst[offset] = *src++;

(gdb) bt
#0  0x083c54a7 in seqvideo_decode_frame (avctx=0x8667180,
data=0xafc43f04, data_size=0xafc44090, buf=0x86eadd0 "\003",
    buf_size=8210) at tiertexseqv.c:131
#1  0x080c1f80 in avcodec_decode_video (avctx=0x8667180,
picture=0xafc43f04, got_picture_ptr=0xafc44090, buf=0x86eadd0 "\003",
    buf_size=8210) at utils.c:899
#2  0x080643ef in output_packet (ist=0x8674c60, ist_index=0,
ost_table=0x8674d30, nb_ostreams=2, pkt=0xafc44748)
    at ffmpeg.c:1101
#3  0x08066343 in main (argc=Cannot access memory at address 0x0
) at ffmpeg.c:1940

Gergory, could please see what's going wrong ? Thanks a lot.

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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