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Digital Signal Processors (DSP)
DaVinci™ Video Processors
DM64x DaVinci Video Processor Forum
mcasp and alsasrc for dm6467
I have a question regarding alsasrc used on a dm6467.
I have a pipeline that capture audio using mcasp (RX_MODE), encode and stream it over the ner (RTP).
I'm observing that it works ok if I set provide-clock=false as alsasrc parameter.
Not good if I set provide-clock=true.
What does it mean?
I'm using MCASP0 in RX_MODE with 2 serializer.
I receive AHCLKR from an external clock (that is clocked with the video clock), to avoid audio-video unsync.
But I don't uderstand how to have 2 input video in sync with the audio if the audio clock of mcasp0 is only one!
how can I provide the real master clock AHCLKR to alsasrc ?
making some progress...
Looking into the /mach-davinci/time.c code ...
/* * Configure the 2 64-bit timer as 4 32-bit timers with * following assignments. * * T0_BOT: Timer 0, bottom: AV Sync * T0_TOP: Timer 0, top: free-running counter, * used for cycle counter * T1_BOT: Timer 1, bottom: reserved for DSP * T1_TOP: Timer 1, top : Linux system tick */ tid_system = T1_TOP; tid_freerun = T0_TOP;
Both system and freerun user internal clock source.
For streaming application, I'm using an external audio master clock (24576000 Hz ) as T0_BOT time. So now I have a clocksource in time with this external clock.
How can provide this audio clock to ALSA ?
I don't see any T0_BOT configuration in the code ...
Is there any place where to set the codec master clock, in order to have a correct configuration for capture timer ?
cat /proc/asound/timersG0: system timer : 10000.000us (10000000 ticks)P0-0-1: PCM capture 0-0-1 : SLAVE
What do you mean with "Not good if I set provide-clock=true" ? provide-clock=true is the default setting and I guess it is working for me on DM6446. I just encounter another problem with alsasrc, as postet in http://e2e.ti.com/support/embedded/linux/f/354/t/182030.aspx#656226
And how do you create a pipe that captures audio using mcasp (RX_MODE) - actually you don't worry about McASP if you are going through ALSA, aren't you? (I guess you are talking about streamer pipes)
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