Carl Eugen Hoyos <[email protected]> added the comment:
Note that "Stream mapping: Stream #1.0 -> #0.1" shows that -ac does not work as
you expect. If you think the documentation is not sufficient, please send a
patch.
Reproducible only on a 32-bit system.
gdb) r -f s16le -i /dev/zero -ac 6 -f wav -y /dev/null
FFmpeg version SVN-r24796, Copyright (c) 2000-2010 the FFmpeg developers
built on Aug 15 2010 20:55:35 with gcc 4.4.4
configuration: --cc='/usr/local/gcc-4.4.4/bin/gcc -m32'
libavutil 50.23. 0 / 50.23. 0
libavcore 0. 4. 0 / 0. 4. 0
libavcodec 52.85. 1 / 52.85. 1
libavformat 52.78. 2 / 52.78. 2
libavdevice 52. 2. 1 / 52. 2. 1
libavfilter 1.34. 1 / 1.34. 1
libswscale 0.11. 0 / 0.11. 0
[s16le @ 0x8bdd490] Estimating duration from bitrate, this may be inaccurate
Input #0, s16le, from '/dev/zero':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0.0: Audio: pcm_s16le, 44100 Hz, 1 channels, s16, 705 kb/s
Output #0, wav, to '/dev/null':
Metadata:
encoder : Lavf52.78.2
Stream #0.0: Audio: pcm_s16le, 44100 Hz, 6 channels, s16, 4233 kb/s
Stream mapping:
Stream #0.0 -> #0.0
Press [q] to stop encoding
Program received signal SIGSEGV, Segmentation fault.
ac3_5p1_mux (n=<value optimized out>, input2=0x10, input1=<value optimized out>,
output=<value optimized out>) at libavcodec/resample.c:134
134 r=*input2++;
(gdb) bt
#0 ac3_5p1_mux (n=<value optimized out>, input2=0x10, input1=<value optimized
out>, output=<value optimized out>) at libavcodec/resample.c:134
#1 audio_resample (n=<value optimized out>, input2=0x10, input1=<value
optimized out>, output=<value optimized out>) at libavcodec/resample.c:340
#2 0x0804ef99 in do_audio_out (s=<value optimized out>, ost=0x8bf0240,
ist=<value optimized out>, buf=0xf7c9e020 "", size=2048) at ffmpeg.c:919
#3 0x080529fc in output_packet (ist=<value optimized out>, ist_index=<value
optimized out>, ost_table=<value optimized out>, nb_ostreams=1, pkt=0xffffce20)
at ffmpeg.c:1700
#4 0x08055b2b in transcode (nb_output_files=<value optimized out>,
nb_input_files=<value optimized out>, nb_stream_maps=<value optimized out>,
stream_maps=<value optimized out>, input_files=<value optimized out>,
output_files=<value optimized out>) at ffmpeg.c:2610
#5 0x080563fb in main (argc=13, argv=0xffffcff4) at ffmpeg.c:4359
(gdb) disass $pc-32 $pc+32
Dump of assembler code from 0x82fb288 to 0x82fb2c8:
0x082fb288 <ac3_5p1_mux+16>: add %al,(%eax)
0x082fb28a <ac3_5p1_mux+18>: add %dh,(%ecx)
0x082fb28c <ac3_5p1_mux+20>: rorb %cl,-0x76cfdb94(%ecx)
0x082fb292 <ac3_5p1_mux+26>: int $0x89
0x082fb294 <ac3_5p1_mux+28>: jl 0x82fb2ba <ac3_5p1_mux+66>
0x082fb296 <ac3_5p1_mux+30>: sub $0x89,%al
0x082fb298 <ac3_5p1_mux+32>: pop %esp
0x082fb299 <ac3_5p1_mux+33>: and $0x34,%al
0x082fb29b <ac3_5p1_mux+35>: nop
0x082fb29c <ac3_5p1_mux+36>: lea 0x0(%esi,%eiz,1),%esi
0x082fb2a0 <ac3_5p1_mux+40>: mov 0x30(%esp),%ecx
0x082fb2a4 <ac3_5p1_mux+44>: movzwl (%ecx,%edx,2),%esi
0x082fb2a8 <ac3_5p1_mux+48>: movzwl 0x0(%ebp,%edx,2),%ecx
0x082fb2ad <ac3_5p1_mux+53>: add $0x1,%edx
0x082fb2b0 <ac3_5p1_mux+56>: movw $0x0,0x6(%eax)
0x082fb2b6 <ac3_5p1_mux+62>: movw $0x0,0x8(%eax)
0x082fb2bc <ac3_5p1_mux+68>: mov %esi,%edi
0x082fb2be <ac3_5p1_mux+70>: mov %ecx,%ebx
0x082fb2c0 <ac3_5p1_mux+72>: shr $0xf,%bx
0x082fb2c4 <ac3_5p1_mux+76>: shr $0xf,%di
End of assembler dump.
(gdb) info registers
eax 0xf7c78020 -137920480
ecx 0x8bfb4d0 146781392
edx 0x0 0
ebx 0x8bf0b20 146737952
esp 0xffffb990 0xffffb990
ebp 0x10 0x10
esi 0x0 0
edi 0x3f6 1014
eip 0x82fb2a8 0x82fb2a8 <ac3_5p1_mux+48>
eflags 0x10246 [ PF ZF IF RF ]
cs 0x23 35
ss 0x2b 43
ds 0x2b 43
es 0x2b 43
fs 0x0 0
gs 0x63 99
----------
priority: normal -> important
substatus: needs_more_info -> reproduced
topic: +avcodec
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FFmpeg issue tracker <[email protected]>
<https://roundup.ffmpeg.org/issue2168>
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