[mythtv-users] Transcode / nuvexport question

Steve Peters - Priority Electronics steve at priorityelectronics.com
Wed Jul 16 23:06:26 UTC 2008


>
>I have some large 1080i files (PBS, Carrier, 2 hours = 12GB) 
>that I'd very much like to compress down to something smaller.
>
>I've tried a few different combinations with nuvexport based 
>on looking at some downloaded xvids that look nice to me.  I'm 
>seeing settings like 500-750 as the width and a corresponding 
>height for 16:9.  Bitrates for a typical download are like 800-1100.
>
>Now if I use nuvexport to transcode a 1080i TV recording down 
>to something like that (which yields like 700MB/hr), it looks terrible.
>
>I'm using xvid, 2 pass, deinterlaced.  I've tried bitrates out 
>to 2000, but it doesn't really get anywhere near the quality 
>I'm seeing from a downloaded copy of Stargate.
>
>What am I doing wrong?  Can someone give me some good 
>nuvexport parameters to turn a 1080i into 700MB/hr and look as 
>nice as what is commonly available via torrent?
>
>Other script? Other procedure?  Abandon xvid for divx?
>
>Also -- how to I tell nuvexport to retain the AC3 soundtrack 
>during the procedure rather than converting to mp3?
>
>Thanks for the help.  I'm new to exporting.
>
>Thanks,
>John.
>
>
>


I'd recommend you check which program is doing the encoding...like are you
using ffmpeg, transcode, or mencoder? I have found time and time again that
mencoder is totally the best. You will get slower encodes, but much much
better quality. I've been doing a lot of transcodes and for a two hour
program, it gets it down to around 600mb and it looks really great. I'm not
using hd source, but rather s-video from my cable box. I imagine that if I
was using an hd source, the image would look even better.

Just be sure to enable noise reduction and enable deinterlacing. My
resolutions are 624 x 352 when I record from an hd channel like pbs hd or
hbo hd. Looks great on a 55" tv.

Instead of double pass, I usually choose vbr quality/quantisation to 4 or 3
(3 being higher quality). Unless you really need a 700mb file, this will
save you a lot of time and get you a great file. If you choose quality 4 and
the file comes out to 600mb and you want better quality, just re-do it at
quality 3. In the end, that will take the same time as a double pass
encoding. Soon, you'll find the quality level setting you're looking for and
will be able to double speed your encodes by not doing multipass.

-Steve




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