On Fri, Dec 17, 2010 at 11:51 AM, Jaroslav Kysela <perex@xxxxxxxx> wrote: > On Fri, 17 Dec 2010, Manu Abraham wrote: > >> On Fri, Dec 17, 2010 at 10:28 AM, Manu Abraham <abraham.manu@xxxxxxxxx> >> wrote: >>> >>> Hi, >>> >>> By now I am a bit confused. >>> >>> I am seeing a certain pattern in which the callbacks are invoked: >>> >>> - hw_params() >>> - prepare() >>> - trigger(); // Start DMA >>> - pointer(); >>> --> gets data after interrupt is handled >>> - trigger(); // Stop DMA >>> - prepare(); >>> - trigger(); // Start DMA >>> - pointer(); >>> --> gets data after interrupt is handled >>> >>> .. >>> .. >>> >>> and so on. >>> >>> Is this the right behaviour that's expected from a function ALSA >>> capture driver ? >>> I am trying to understand why there is Start DMA, Stop DMA, Start DMA, >>> Stop DMA >>> in a cyclic fashion for each of the interrupts in my setup. >> >> >> To test my theory that a STOP cmd after an interrupt was giving me the >> same buffer location, I did commented out the STOP cmd, as well, >> allowing the START cmd to run only if the streaming engine has not >> START 'ed. >> >> This allows the interrupt handler to fire correctly with the correct >> buffer indices, as seen in the following logs. >> >> http://pastebin.ca/2021840 >> >> The problem is that, >> >> 1. I don't understand why the application issues a CMD to STOP/START, >> after each interrupt. >> 2. The STOP/START cmds reinitializes the Streaming engine to start >> with buffer index:0, therefore always buffer position is at the very >> beginning of the buffer. > > I believe that your pointer callback is buggy so the midlevel code things > that you had and overrun. > > http://www.alsa-project.org/main/index.php/XRUN_Debug Thanks, that was very helpful. I am looking at it. I did find an issue looking at the pointer callback itself straight away. static snd_pcm_uframes_t saa7231_capture_pointer(struct snd_pcm_substream *pcm) { struct saa7231_audio *audio = snd_pcm_substream_chip(pcm); struct saa7231_dev *saa7231 = audio->saa7231; struct snd_pcm_runtime *rt = pcm->runtime; dprintk(SAA7231_DEBUG, 1, "DEBUG:()"); return bytes_to_frames(rt, audio->index * audio->pages * PAGE_SIZE); } audio->pages is the whole number of pages for all the 8 buffers; Fixed that issue, run it again, this time arecord stated just a single overrun static snd_pcm_uframes_t saa7231_capture_pointer(struct snd_pcm_substream *pcm) { struct saa7231_audio *audio = snd_pcm_substream_chip(pcm); struct saa7231_dev *saa7231 = audio->saa7231; struct snd_pcm_runtime *rt = pcm->runtime; u32 frames; frames = bytes_to_frames(rt, audio->index * (audio->pages / XS2D_BUFFERS) * PAGE_SIZE); dprintk(SAA7231_DEBUG, 1, "DEBUG:() Index:%d with frames:%d, total %d pages", audio->index, frames, audio->pages); return frames; } testbox v4l # arecord -D plughw:2,0 --format S16_LE --rate=48000 -c 2 > /tmp/test.wav Recording WAVE 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo overrun!!! (at least 0.006 ms long) ^CAborted by signal Interrupt... The logs do look thus now: http://pastebin.ca/2021872 Now, I do get a .wav file The contents of which seems to be junk ?? http://202.88.242.108:8000/test/test.wav Tried to play it back with alsaplayer and mplyer with no results, mplayer shows no issues though.. Maybe PCM corruptions ? But at least some noises it should make ? Thanks, Manu manu@manu-04:~$ mplayer ~/test.wav MPlayer SVN-r1.0~rc3+svn20090426-4.4.3 (C) 2000-2009 MPlayer Team mplayer: could not connect to socket mplayer: No such file or directory Failed to open LIRC support. You will not be able to use your remote control. Playing /home/manu/test.wav. Audio only file format detected. ========================================================================== Opening audio decoder: [pcm] Uncompressed PCM audio decoder AUDIO: 48000 Hz, 2 ch, s16le, 1536.0 kbit/100.00% (ratio: 192000->192000) Selected audio codec: [pcm] afm: pcm (Uncompressed PCM) ========================================================================== AO: [pulse] Init failed: Connection refused Failed to initialize audio driver 'pulse' AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample) Video: no video Starting playback... A: 9.0 (09.0) of 25.0 (25.0) 0.0% MPlayer interrupted by signal 2 in module: key_events A: 9.0 (09.0) of 25.0 (25.0) 0.0% Exiting... (Quit) manu@manu-04:~$ _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
