$ gdb ./ffmpeg_g 
GNU gdb (GDB) 7.4.1-debian
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/adriano/ffmpeg_git/ffmpeg/ffmpeg_g...done.
(gdb) r -f alsa -ar 8000 -ac 1 -i hw:1,0 -ar 8000 -acodec pcm_alaw -ab 64k -f rtp rtp://127.0.0.1:1234
Starting program: /home/adriano/ffmpeg_git/ffmpeg/ffmpeg_g -f alsa -ar 8000 -ac 1 -i hw:1,0 -ar 8000 -acodec pcm_alaw -ab 64k -f rtp rtp://127.0.0.1:1234
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/i686/cmov/libthread_db.so.1".
ffmpeg version N-41796-g1bb30d0 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jun 22 2012 10:56:44 with gcc 4.6.3
  configuration: --enable-libx264 --enable-gpl
  libavutil      51. 59.100 / 51. 59.100
  libavcodec     54. 29.100 / 54. 29.100
  libavformat    54. 10.100 / 54. 10.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 82.100 /  2. 82.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
[alsa @ 0x8f524c0] Estimating duration from bitrate, this may be inaccurate
Guessed Channel Layout for  Input Stream #0.0 : mono
Input #0, alsa, from 'hw:1,0':
  Duration: N/A, start: 1340369169.952557, bitrate: 705 kb/s
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
[aformat @ 0x8f50b00] auto-inserting filter 'auto-inserted resampler 0' between the filter 'Parsed_anull_0' and the filter 'aformat'
[auto-inserted resampler 0 @ 0x8f519a0] chl:mono fmt:s16 r:44100Hz -> chl:mono fmt:s16 r:8000Hz
[rtp @ 0x8f4c940] Cannot respect max delay: frame size = 0
Output #0, rtp, to 'rtp://127.0.0.1:1234':
  Metadata:
    encoder         : Lavf54.10.100
    Stream #0:0: Audio: pcm_alaw, 8000 Hz, mono, s16, 64 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le -> pcm_alaw)
SDP:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
a=tool:libavformat 54.10.100
m=audio 1234 RTP/AVP 8
b=AS:64

Press [q] to stop, [?] for help
size=     883kB time=00:00:53.89 bitrate= 134.2kbits/s    
Program received signal SIGSEGV, Segmentation fault.
0x080ab79f in avfilter_copy_buffer_ref_props (dst=0x0, src=0x8f6b280)
    at libavfilter/buffer.c:169
169	    dst->pts             = src->pts;
(gdb) bt
#0  0x080ab79f in avfilter_copy_buffer_ref_props (dst=0x0, src=0x8f6b280)
    at libavfilter/buffer.c:169
#1  0x080d18c6 in filter_samples (inlink=0x8f51020, insamplesref=0x8f6b280)
    at libavfilter/af_aresample.c:178
#2  0x080a745a in ff_filter_samples (link=0x8f51020, samplesref=0x8f6b280)
    at libavfilter/audio.c:213
#3  0x080a745a in ff_filter_samples (link=0x8f50f60, samplesref=0x8f6b280)
    at libavfilter/audio.c:213
#4  0x080abe68 in request_frame (link=0x8f50f60) at libavfilter/buffersrc.c:445
#5  0x080a95bf in ff_request_frame (link=0x8f51020)
    at libavfilter/avfilter.c:325
#6  avfilter_request_frame (link=0x8f51020) at libavfilter/avfilter.c:594
#7  0x080d1744 in request_frame (outlink=0x8f517c0)
    at libavfilter/af_aresample.c:214
#8  0x080a880f in ff_request_frame (link=0x8f51100)
    at libavfilter/avfilter.c:325
#9  0x080abab8 in av_buffersink_read (ctx=0x8f50760, buf=0xbfffe518)
    at libavfilter/buffersink.c:109
#10 0x08095d7f in poll_filters () at ffmpeg.c:1928
#11 0x08099f64 in transcode () at ffmpeg.c:3612
#12 0x0808cf6a in main (argc=<optimized out>, argv=<optimized out>)
    at ffmpeg.c:5921
(gdb) disass $pc-32,$pc+32
Dump of assembler code from 0x80ab77f to 0x80ab7bf:
   0x080ab77f <avfilter_unref_bufferp+15>:	(bad)  
   0x080ab780 <avfilter_unref_bufferp+16>:	(bad)  
   0x080ab781 <avfilter_unref_bufferp+17>:	inc    %edi
   0x080ab783 <avfilter_unref_bufferp+19>:	add    (%eax),%eax
   0x080ab785 <avfilter_unref_bufferp+21>:	add    %al,(%eax)
   0x080ab787 <avfilter_unref_bufferp+23>:	add    %al,-0x3ca4e73c(%ebx)
   0x080ab78d:	lea    0x0(%esi),%esi
   0x080ab790 <avfilter_copy_buffer_ref_props+0>:	push   %ebx
   0x080ab791 <avfilter_copy_buffer_ref_props+1>:	mov    0xc(%esp),%eax
   0x080ab795 <avfilter_copy_buffer_ref_props+5>:	mov    0x8(%esp),%edx
   0x080ab799 <avfilter_copy_buffer_ref_props+9>:	mov    0x48(%eax),%ecx
   0x080ab79c <avfilter_copy_buffer_ref_props+12>:	mov    0x4c(%eax),%ebx
=> 0x080ab79f <avfilter_copy_buffer_ref_props+15>:	mov    %ecx,0x48(%edx)
   0x080ab7a2 <avfilter_copy_buffer_ref_props+18>:	mov    0x50(%eax),%ecx
   0x080ab7a5 <avfilter_copy_buffer_ref_props+21>:	mov    %ebx,0x4c(%edx)
   0x080ab7a8 <avfilter_copy_buffer_ref_props+24>:	mov    0x54(%eax),%ebx
   0x080ab7ab <avfilter_copy_buffer_ref_props+27>:	mov    %ecx,0x50(%edx)
   0x080ab7ae <avfilter_copy_buffer_ref_props+30>:	mov    0x5c(%eax),%ecx
   0x080ab7b1 <avfilter_copy_buffer_ref_props+33>:	mov    %ebx,0x54(%edx)
   0x080ab7b4 <avfilter_copy_buffer_ref_props+36>:	test   %ecx,%ecx
   0x080ab7b6 <avfilter_copy_buffer_ref_props+38>:	jne    0x80ab7f0 <avfilter_copy_buffer_ref_props+96>
---Type <return> to continue, or q <return> to quit---
   0x080ab7b8 <avfilter_copy_buffer_ref_props+40>:	mov    0x60(%eax),%eax
   0x080ab7bb <avfilter_copy_buffer_ref_props+43>:	mov    0x60(%edx),%edx
   0x080ab7be <avfilter_copy_buffer_ref_props+46>:	mov    (%eax),%ecx
End of assembler dump.
(gdb) info all-registers
eax            0x8f6b280	150385280
ecx            0x33aaa9e	54176414
edx            0x0	0
ebx            0x0	0
esp            0xbfffddc8	0xbfffddc8
ebp            0x0	0x0
esi            0x8f51020	150278176
edi            0x8f6b280	150385280
eip            0x80ab79f	0x80ab79f <avfilter_copy_buffer_ref_props+15>
eflags         0x210286	[ PF SF IF RF ID ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x33	51
st0            0.0096715819061950827895124405131355161	(raw 0x3ff89e758dff365da000)
st1            2.4075930937553908783854694775072858	(raw 0x40009a160157f04fb800)
st2            2.4075930937553908783854694775072858	(raw 0x40009a160157f04fb800)
st3            0.019157279608339034676633971798764833	(raw 0x3ff99cefba2cbd982---Type <return> to continue, or q <return> to quit---
800)
st4            -108000000000	(raw 0xc023c92a69c000000000)
st5            1000000	(raw 0x4012f424000000000000)
st6            4	(raw 0x40018000000000000000)
st7            0.72562358276643990073750956071307883	(raw 0x3ffeb9c27795302e7000)
fctrl          0x37f	895
fstat          0x120	288
ftag           0xffff	65535
fiseg          0x73	115
fioff          0x80d1892	135075986
foseg          0x7b	123
fooff          0xbfffde0c	-1073750516
fop            0x35c	860
xmm0           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
xmm1           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
xmm2           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
---Type <return> to continue, or q <return> to quit---
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
xmm3           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {
    0x8000000000000000, 0x8000000000000000}, v16_int8 = {0x0, 0x0, 0x0, 
    0xff <repeats 13 times>}, v8_int16 = {0x0, 0xff00, 0xffff, 0xffff, 0xffff, 
    0xffff, 0xffff, 0xffff}, v4_int32 = {0xff000000, 0xffffffff, 0xffffffff, 
    0xffffffff}, v2_int64 = {0xffffffffff000000, 0xffffffffffffffff}, 
  uint128 = 0xffffffffffffffffffffffffff000000}
xmm4           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
xmm5           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
xmm6           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
xmm7           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, 
  v16_int8 = {0x0 <repeats 16 times>}, v8_int16 = {0x0, 0x0, 0x0, 0x0, 0x0, 
---Type <return> to continue, or q <return> to quit---
    0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, 
  uint128 = 0x00000000000000000000000000000000}
mxcsr          0x1f80	[ IM DM ZM OM UM PM ]
mm0            {uint64 = 0x9e758dff365da000, v2_int32 = {0x365da000, 
    0x9e758dff}, v4_int16 = {0xa000, 0x365d, 0x8dff, 0x9e75}, v8_int8 = {0x0, 
    0xa0, 0x5d, 0x36, 0xff, 0x8d, 0x75, 0x9e}}
mm1            {uint64 = 0x9a160157f04fb800, v2_int32 = {0xf04fb800, 
    0x9a160157}, v4_int16 = {0xb800, 0xf04f, 0x157, 0x9a16}, v8_int8 = {0x0, 
    0xb8, 0x4f, 0xf0, 0x57, 0x1, 0x16, 0x9a}}
mm2            {uint64 = 0x9a160157f04fb800, v2_int32 = {0xf04fb800, 
    0x9a160157}, v4_int16 = {0xb800, 0xf04f, 0x157, 0x9a16}, v8_int8 = {0x0, 
    0xb8, 0x4f, 0xf0, 0x57, 0x1, 0x16, 0x9a}}
mm3            {uint64 = 0x9cefba2cbd982800, v2_int32 = {0xbd982800, 
    0x9cefba2c}, v4_int16 = {0x2800, 0xbd98, 0xba2c, 0x9cef}, v8_int8 = {0x0, 
    0x28, 0x98, 0xbd, 0x2c, 0xba, 0xef, 0x9c}}
mm4            {uint64 = 0xc92a69c000000000, v2_int32 = {0x0, 0xc92a69c0}, 
  v4_int16 = {0x0, 0x0, 0x69c0, 0xc92a}, v8_int8 = {0x0, 0x0, 0x0, 0x0, 0xc0, 
    0x69, 0x2a, 0xc9}}
mm5            {uint64 = 0xf424000000000000, v2_int32 = {0x0, 0xf4240000}, 
  v4_int16 = {0x0, 0x0, 0x0, 0xf424}, v8_int8 = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 
    0x24, 0xf4}}
mm6            {uint64 = 0x8000000000000000, v2_int32 = {0x0, 0x80000000}, 
  v4_int16 = {0x0, 0x0, 0x0, 0x8000}, v8_int8 = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 
---Type <return> to continue, or q <return> to quit---
    0x0, 0x80}}
mm7            {uint64 = 0xb9c27795302e7000, v2_int32 = {0x302e7000, 
    0xb9c27795}, v4_int16 = {0x7000, 0x302e, 0x7795, 0xb9c2}, v8_int8 = {0x0, 
    0x70, 0x2e, 0x30, 0x95, 0x77, 0xc2, 0xb9}}
(gdb)