Mauro Carvalho Chehab wrote: > I'm getting an weird behavior with em28xx, especially when the device > is connected into an audio port. > > http://git.linuxtv.org/mchehab/experimental.git/blob/refs/heads/em28xx-v4l2-v6:/drivers/media/usb/em28xx/em28xx-audio.c > > What happens is that, when I require xawtv3 to use any latency lower > than 65 ms, the audio doesn't work, as it gets lots of underruns per > second. The driver uses five URBs with 64 frames each, so of course it will not be able to properly handle periods smaller than that. > FYI, em28xx works at a 48000 KHz sampling rate, and its PM capture Hw > is described as: > > static struct snd_pcm_hardware snd_em28xx_hw_capture = { > .info = SNDRV_PCM_INFO_BLOCK_TRANSFER | > SNDRV_PCM_INFO_MMAP | > SNDRV_PCM_INFO_INTERLEAVED | > SNDRV_PCM_INFO_BATCH | > SNDRV_PCM_INFO_MMAP_VALID, > > .formats = SNDRV_PCM_FMTBIT_S16_LE, > > .rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_KNOT, This should be just SNDRV_PCM_RATE_48000. > .period_bytes_min = 64, /* 12544/2, */ This is wrong (if the driver doesn't install other constraints on the period length, like the USB audio class driver does). Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
