[mythtvnz] 0.25 video frame jitter.

[Jean-Yves Avenard]

On 7 April 2012 20:19, Brett <mythicalbeast at slingshot.co.nz> wrote:
> Using default value of 64:
> This value does not cause jitter problems with all recordings.
> High data rate recordings, with AC3 only, play well by IEC958 pass-thru'
> e.g. Samsung HD demo h264 30p 40Mbps AC3 448Kbps plays perfectly as
> pass-thru' but jitter increases/deteriorates when using decoded PCM
> output.

64kB is only good enough for stereo output (that includes AC3 and DTS
which fundamentally are 44.1-48kHz stereo PCM streams)

More than that, in particular LPCM multichannels stream and you will
get buffer underruns.

Ubuntu sets the default alsa buffer to 4MB.
When using TrueHD or DTS-HD MA, which are 16 bits, 8 channels, 192kHz
PCM. You'll need close to 4MB.
So setting 4MB alsa buffer is actually a value that makes sense and
that will work across the spectrum of content you could play