[mythtvnz] Anyone successfully using CoreAVC for h264 decoding ?

[Steven Ellis]

On 1/09/2008, at 8:00 PM, Graeme Woollett wrote:

> After I included the cp directshow came to life  :-)
> TV3 is now watchable but large screen changes/movement are not fluid.
>
> dhsowserver CPU usage varies a lot, between 90and 120%/40% idle for  
> TV3
> with the "normal" playback profile
>
> TV1&2 are around 70-80% with Piha rescue, this prog is not HD though
>
> front end is crashing reasonably frequently with the following-
> 2008-09-01 19:00:37.711 AFD: Found DirectShow filter
> 2008-09-01 19:00:37.712 AFD: Opened codec 0xa8f35c30, id(H264)  
> type(Video)
> 2008-09-01 19:00:37.712 AFD: codec AAC_LATM has 2 channels
> 2008-09-01 19:00:37.712 AFD Error: Could not find decoder for codec
> (AAC_LATM), ignoring.
> 2008-09-01 19:00:37.712 AFD: codec AC3 has 6 channels
> 2008-09-01 19:00:37.712 AFD: Opened codec 0xa8faae30, id(AC3)  
> type(Audio)
> 2008-09-01 19:00:39.054 NVP: Prebuffer wait timed out 10 times.
> 2008-09-01 19:10:14.446 Mixer unable to find control Master 1
> 2008-09-01 19:10:14.446 mixer unable to find control Master 1
> Segmentation fault
>
> myth at mercury:~$ Parent process 21839 died unexpectedly
>
> the aac_Latm error I guess is largely due to a fix in avformat.cpp  
> that
> allowed it to compile cleanly
>
> 2008-09-01 19:49:05.089 AFD: Opened codec 0xa6411f80, id(H264)  
> type(Video)
> 2008-09-01 19:49:05.089 AFD: codec AAC_LATM has 2 channels
> 2008-09-01 19:49:05.089 AFD Error: Could not find decoder for codec
> (AAC_LATM), ignoring.
> 2008-09-01 19:49:05.089 AFD: Opened codec 0xa64b40a0, id(DVB_SUBTITLE)
> type(Subtitle)
> 2008-09-01 19:49:05.089 NVP: Disabling Audio, params(0,-1,-1)
> 2008-09-01 19:49:41.475 NVP: prebuffering pause
> 2008-09-01 19:50:05.244 NVP: prebuffering pause
>
>
> On TV1 and 2 with this build I don't have any sound, TV3 DVB-T and  
> DVB-S
> are OK
>
> The directshow build is less stable than others, I think I'll need to
> stick with DVB-S a little longer or the WAF will take a hammering...
>

New tests with CoreAVC 1.7. CPU is 3600+ running in performance mode  
of 2GHz. and CPU scaling disabled

Channel	resolution	dshowfilter	mythfrontend
freeview|HD	720p	78	20
TV One	720p	84	22
TV 2	720p	75	22
TV 3	1080i	150	22
C4	576i	34	7
TVNZ 6	576i	30	7
TVNZ 7	576i	21	7

Some odd issues when switching between 720p and interlaced channels,  
but otherwise load is ok even on TV3.

The mythfrontend load is reasonably reliable.

I also tried tweaking the de-blocking settings

~/bin/registercodec -r $REGISTRY -k \
"HKLM\\Software\\IniFileMapping\\CoreAVC\\Settings\\C:\\coreavc.ini" \
-v "deblock=9"

This appeared to reduce the CPU load by a few more percent.

Unlike Graeme I managed to get working audio on all of the channels.

Not really a bullet proof solution yet. Load is a lot better than pure  
ffmpeg thanks to the CPU threading support, but I have a feeling if  
ffmpeg gets better multi-core support it will beat CoreAVC.

Sadly the quality isn't there though. The Interlaced channels look a  
little bit scrappy.

I think we need to hold out for better threading support in ffmpeg, or  
the GSoC performance improvements using the GPU to accelerate the  
decode.

Steve



Steven Ellis - Technical Director
OpenMedia Limited
email   - steven at openmedia.co.nz
website - http://www.openmedia.co.nz

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