[mythtv-users] Transcoding and H264

spencer.herzberg at gmail.com spencer.herzberg at gmail.com
Mon Jan 31 18:04:42 UTC 2011

I would be interested in your (Robert's) userjob if you wouldn't mind
posting it to the mailing list. Otherwise, a reply to my email would be


On Mon, Jan 31, 2011 at 12:53 PM, Robert Houghton <robbadler at gmail.com>wrote:

> On Sun, Jan 30, 2011 at 11:17 AM, Jeffrey J. Kosowsky <mythtv at kosowsky.org
> > wrote:
>> I have been a longtime user of mythtranscode/mpeg4 which I use to
>> transcode my OTA mpeg2 recordings to mpeg4 compressed down to
>> 1-1.5GB/hour.
>> However, given the current problem with 6 channel transcoding plus the
>> general sense that mythtranscode is long in the tooth and lagging
>> H264, I am interested in switching to H264 transcoding.
>> I have several questions:
>> 1. In general how much slower will H264 *encoding* be relative to
>>   mythtranscode Mpeg4? (I have an old/slow machine and slow graphic card)
>> On a dual-core 2.5Ghz I get about 14FPS using ffmpeg with the high-quality
> preset, recording at 3Mbps with 5.1 AAC audio
> 2. Similarly, how much slower will *decoding* be?
> Not recognizable, since I have VDPAU capable cards, or stream to a PS3 via
> uPNP
>> 3. Are there any plug-ins available to automate such transcoding?
> I can post my userjob if requested
>> 4. If not are there Job scripts and instructions available?
>>   (note: I checked http://mythtv.org/wiki/Category:User_Job_Scripts
>>   but didn't see much other than "Transcode wrapper stub" which
>>   seemed to only be part of the solution)
> See (3)
>> 5. What is a "reasonable" bandwidth expectation for good quality H264
>>   in 1080 and/or 720p?
>>   (Note with mp4 I was using 1-1.5GB/hour. What type of quality can I
>>   expect with H264 in that bandwidth range?)
> As said, I record at 3Mbps at 720p. I also de-interlace and change the
> audio codec to something my PS3 can play. This gives me at or under 1Gb per
> hour (42minutes) of video.
>> Basically, I would like something that will automatically transcode
>> all new digital recordings to H264 with some ability to set the
>> bandwidth/disk space used. If it is a script, I want to be able to
>> either manually or automatically start it and then have the script
>> take over to launch the right transcoding codec, do the transcoding,
>> remove the original when done, and then update the mythdatabase when
>> done.
>> Sorry if any of my questions seem too newbie but I just am not
>> experienced in this and I *know* that others must have solved this
>> problem many times over.
>> Thanks!
>> _______________________________________________
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>> mythtv-users at mythtv.org
>> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
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