[FFmpeg-user] How to set sample format for the alsa demuxer?

[LANGLOIS Olivier PIS -EXT]

I want to set the input sample format to s32 but I failed to change it from its S16_LE default format.

Am I doing something wrong or did I have stumbled onto a small ffmpeg bug?

lano1106 at hpmini ~/dev/packages/ffmpeg/repos/extra-i686/src/ffmpeg-2.1.1/libavdevice :( $ ffmpeg -f alsa -sample_fmt s32 -i hw:1,1,0 -strict -2 -acodec aac -ar 48000 -b:a 64k out.aac
ffmpeg version 2.1.1 Copyright (c) 2000-2013 the FFmpeg developers
  built on Dec 10 2013 17:24:34 with gcc 4.8.2 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --enable-avresample --enable-dxva2 --enable-fontconfig --enable-gnutls --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-pic --enable-postproc --enable-runtime-cpudetect --enable-shared --enable-swresample --enable-vdpau --enable-version3 --enable-x11grab
  libavutil      52. 48.101 / 52. 48.101
  libavcodec     55. 39.101 / 55. 39.101
  libavformat    55. 19.104 / 55. 19.104
  libavdevice    55.  5.100 / 55.  5.100
  libavfilter     3. 90.100 /  3. 90.100
  libavresample   1.  1.  0 /  1.  1.  0
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
[alsa @ 0x8b2afa0] cannot set sample format 0x10000 2 (Invalid argument)
hw:1,1,0: Input/output error

>From ffmpeg header files:
avcodec.h:    AV_CODEC_ID_PCM_S16LE = 0x10000,
alsa-audio.h:#define DEFAULT_CODEC_ID AV_NE(AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE)

Here is what I have done to reproduce the problem. I am sending ALSA speaker-test output through the ALSA loopback driver. If I modify the speaker-test output sample format to S16_LE all is fine.

lano1106 at hpmini ~/ffmpeg $ sudo modprobe snd_aloop
[sudo] password for lano1106:
lano1106 at hpmini ~/ffmpeg $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: 92HD81B1X5 Analog [92HD81B1X5 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7

>From a different console, I send speaker-test output:

lano1106 at hpmini ~/ffmpeg $ speaker-test -Dhw:1,0,0 -c2 -r192000 -F S32_LE

speaker-test 1.0.27.2

Playback device is hw:1,0,0
Stream parameters are 192000Hz, S32_LE, 2 channels
Using 16 octaves of pink noise
Rate set to 192000Hz (requested 192000Hz)
Buffer size range from 8 to 262144
Period size range from 8 to 131072


________________________________
CONFIDENTIALITY : This e-mail and any attachments are confidential and may be privileged. If you are not a named recipient, please notify the sender immediately and do not disclose the contents to another person, use it for any purpose or store or copy the information in any medium.