Re: [alsa-devel] trace PCM data from usb bus to alsa lib
At Wed, 17 Jun 2009 16:10:26 +0800, Zero Luo wrote:
Dear Takashi, Data from usb dongle is 16K*16 bit PCM data.
And what is the format and channels you are using in alsa-lib? alsa-lib itself can convert formats and channels automatically if needed.
Takashi
2009/6/17, Takashi Iwai tiwai@suse.de:
At Wed, 17 Jun 2009 07:25:25 +0000 (UTC), ZeroCluo wrote: > > Hi > > I am trying to trace the Audio data from usb bus. > in kernel: > dump data in retire_capture_urb() ,found data format is like: > AABB 0000 CCDD 0000 ; > > but in alsa library , > dump data in snd_pcm_mmap_begin(),the "0000" is cut,only "AABB CCDD", > > Do you know when and where those "0000" is cut? Are you using the native format that the hardware runs? Takashi
Takashi Iwai <tiwai <at> suse.de> writes:
At Wed, 17 Jun 2009 16:10:26 +0800, Zero Luo wrote:
Dear Takashi, Data from usb dongle is 16K*16 bit PCM data.
And what is the format and channels you are using in alsa-lib? alsa-lib itself can convert formats and channels automatically if needed.
Takashi
In alsa-lib ,I set data format as 8K * mulaw . hwparams.format = SND_PCM_FORMAT_MU_LAW; hwparams.rate = 8000; hwparams.channels = 1; Yes,indeed alsa-lib help to convert formats.But before alsa-lib convert pcm data to mulaw,I dumped the src data in snd_pcm_mulaw_encode() which already has no "0000" .
Zero
At Wed, 17 Jun 2009 08:33:15 +0000 (UTC), ZeroCluo wrote:
Takashi Iwai <tiwai <at> suse.de> writes:
At Wed, 17 Jun 2009 16:10:26 +0800, Zero Luo wrote:
Dear Takashi, Data from usb dongle is 16K*16 bit PCM data.
And what is the format and channels you are using in alsa-lib? alsa-lib itself can convert formats and channels automatically if needed.
Takashi
In alsa-lib ,I set data format as 8K * mulaw . hwparams.format = SND_PCM_FORMAT_MU_LAW; hwparams.rate = 8000; hwparams.channels = 1; Yes,indeed alsa-lib help to convert formats.But before alsa-lib convert pcm data to mulaw,I dumped the src data in snd_pcm_mulaw_encode() which already has no "0000" .
Well, another question is whether the output result is correct. Did you get broken output or so?
Takashi
Well, another question is whether the output result is correct. Did you get broken output or so?
Takashi
First,thanks for your reply.
Output should be correct.I can hear smooth voice. It real confuse me...
Zero
participants (2)
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Takashi Iwai -
ZeroCluo