[mythtv-users] Suggested Encoding Rates

Jason McLeod anakin at sdf1.net
Thu Apr 28 18:53:18 UTC 2005


I found some video guys here at work, who know a few things about  
video encoding.

They where telling me that the NTSC standard is 720x480, although  
cable broadcasts don't use that high, it's much closer to 480x320.  I  
originally had my resolution for capturing set to the max, but I'll  
try scaling it down to the true broadcast size, that should save some  
space.

Since I'm using a very weak box to run the Myth backend on, I'd  
rather have the size determined while the card is encoding with the  
hardware MPEG2 encoder.

-Jason

Blog: http://jason.sdf1.net
GPG Fingerprint:
anakin at sdf1.net - A6CC 40B4 99A4 1C08 55A7  BCFC ECDF ED68 115E 5993


On 28-Apr-05, at 1:35 PM, Timothy Daniel Hamer wrote:

> On Thu, 28 Apr 2005, Scott Alfter wrote:
>
>
>> Neil Bird wrote:
>>
>>>   I was just about to post this and a related question.  I'm  
>>> running my
>>> PVR-350 with fairly high (normally) res. PAL settings, and a  
>>> bitrate of
>>> ~6200 somethings.  I get images of ~2.0-2.2 Gb per hour.
>>>
>>>   Now, I just downloaded [bittorrent] an episode of something I  
>>> missed.
>>>  The AVI's ~364 Mb for the, I guess, ~43 mins., but is, whem played
>>> through MythVideo, of comparable quality to the stuff I record at  
>>> 6x the
>>> size!
>>>
>>
>> Those AVIs you downloaded probably aren't using MPEG-2, but  
>> instead use some
>> variant or another of MPEG-4.  That's why they can deliver the  
>> same quality in
>> less space.  Comparing MPEG-4 to MPEG-2 is like comparing Ogg  
>> Vorbis to MP3.
>>
>> You could transcode from MPEG-2 to MPEG-4 (MythTV will even do  
>> this for you),
>> but the transcoded recordings won't be playable through your  
>> PVR-350.  (That
>> assumes you're using its MPEG-2 decoder; I stopped using mine when  
>> I upgraded
>> to an LCD TV and switched from S-video to DVI.)
>>
>>  _/_
>> / v \ Scott Alfter (remove the obvious to send mail)
>> (IIGS( http://alfter.us/            Top-posting!
>> \_^_/ rm -rf /bin/laden            >What's the most annoying thing  
>> on Usenet?
>>
>>
>
> I noticed the same thing with downloaded files vs. files captured  
> from my pvr 150, but even when i use mythtranscode to convert them  
> to mpeg-4, i can get downloaded AVI files that look much better and  
> are smaller. Should i use one of the external transcoding programs  
> instead of mythtranscode?
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