[mythtv] ffmpeg sync

John reidjr at btconnect.com
Sun Oct 14 21:36:26 UTC 2007

Janne Grunau wrote:
> On Sunday 14 October 2007 01:53:39 Rudy Zijlstra wrote:
>> Mark Kendall wrote:
>>> On 10/12/07, Janne Grunau <janne-mythtv at grunau.be> wrote:
>>>> Please test and report any problems. Patches apply with -p2.
>>> No obvious issues over a couple of hours of viewing.
>>> BBC-HD (DVB-S) is still problematic - it is clearly using both
>>> cores (Core2Duo E6600) but one is pegged at almost 100%, the other
>>> 60-80% and I get minor pauses every 3-4 seconds. Live tv is worse
>>> than recorded material.
>> With a AMD X2 4600+ i get both cores regularly going to 90% load on
>> BBC-HD. Problem is that the video is not fluent though, lots of
>> micro-pauses. Its almost watchable....
> please try attached patch.
> Janne

Once I got over the apparent dependency on gcc version (gcc-2.95 and 
gcc-4.1 both failed to compile the ffmpeg patch for some reason, seems 
like a known issue) and compiled with gcc-3.4, I used both the main, and 
additional patch.

On a e4300 (1.8GHz core2duo) I could watch BBC-HD with glitches every 
second, even though the resource meter suggested I was using only 80% CPU.

Overclocked the e4300 to 2.4GHz, and I was getting 75-80%  cpu, evenly 
across both cores, and smooth playback. Excellent, so at least on the 
samples I tried, the slice based multi threading (whatever that means 
:-) ) was working perfectly for BBC-HD.

For performance comparison :

I run my 2 "production" frontends on a single cored 3200+ Athlon64  and 
on a e4300 core2duo. I am currently running svn r14404, (last before 
myth-vid sync) with a patch to allow coreavc support. With everything 
turned off (de-interlacing, de-blocking) I get about 60% across both 
cores on the e4300 watching on a 1680x1050 monitor.

I am using the 3200+ as a living room box teamed up with a SD CRT TV.  I 
was surprised to find I NEARLY get away with watching BBC-HD (albeit 
scaled to SD through tv out on an nvidia 6200 card).  The 3200+, is 
running at stock speed in an IWILL ZPCsp64. Unfortunately its a great 
little bookshelf PC, but the BIOS doesn't allow any over clock. I have 
the ddr400 ram as a matched 256M pair, in dual channel mode. The ram 
bandwidth seems to make a difference, and I can watch BBC-HD with few 
enough glitches to be bearable.


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