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Old 26th September 2008, 14:41   #1  |  Link
russellhq
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What Should I Do - Want To Shrink MPEG2 TV caps

I've got a bunch of MPEG 2 video files that I captured straight off my TV card here in the UK. The files are basically the broadcasted streams (digital TV) saved as mpegs.


I've been out of the encoding scene for a few years now and have just come back to it.

I want to compress these files so they don't take up so much space. I think they are currently around 2GIG for an hours video. Not very efficient given the source.

What would be my best bet for encoding them?

They are standard definition PAL (can't think of the resolution off the top of my head)

I'll be doing it on Linux.

Cheers!
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Old 26th September 2008, 14:52   #2  |  Link
linyx
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Use AviDemux to encode them to x264. Works on linux and its pretty good.
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Old 26th September 2008, 14:57   #3  |  Link
russellhq
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Is that a preferred format over DIVX or XviD etc?

How's the encoding speed compared to the last 2?

What would be the preferred profile to use for this type of source?

What sort of bit rate could I expect to see with x264?

My current caps average around 4.5Mbps, idealy I would like something around 1-2Mbps. They are not of exceptional quality.
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Old 26th September 2008, 15:39   #4  |  Link
nm
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Quote:
Originally Posted by russellhq View Post
Is that a preferred format over DIVX or XviD etc?
Depends on the purpose (older hardware players don't support H.264), but generally yes.

Quote:
How's the encoding speed compared to the last 2?
x264 is probably faster for the same level of quality. It is also very well threaded, so it scales up nicely if you have a multicore CPU.

Quote:
What would be the preferred profile to use for this type of source?
x264 itself doesn't have presets and I don't think Avidemux has either. Some other (Windows-based) GUIs have encoding profiles that you can check out if you want.
Avidemux Wiki has a nice article on the settings though: http://www.avidemux.org/admWiki/index.php?title=H264

I'd recommend CRF encoding mode ("Single Pass - Quality Quantizer (Average)" in Avidemux). Try crf=22 first and lower it if the quality is too low, or raise if the output is too large.

Quote:
What sort of bit rate could I expect to see with x264?
That depends on the quality that you expect and the time spent on tweaking filters. But 1-2 Mbps should be quite enough for most PAL DVB sources.

Last edited by nm; 26th September 2008 at 15:43.
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Old 26th September 2008, 20:31   #5  |  Link
laserfan
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Another option if you don't want to re-encode at all could be Super MPEG2 Transcoder. Not free, and maybe overkill for what you want to do (I bought it for shrinking HD MPEG2 files, works great) but there's a free trial version you might want to take for a spin...
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Old 26th September 2008, 23:55   #6  |  Link
nm
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Another option if you don't want to re-encode at all could be Super MPEG2 Transcoder. Not free, and maybe overkill for what you want to do (I bought it for shrinking HD MPEG2 files, works great) but there's a free trial version you might want to take for a spin...
I would call that the quick-and-dirty solution instead of overkill. There are many similar MPEG-2 re-quantizers around, some even available as native Linux programs (Vamps, for example). They are fast, but with a DVB source and low target bitrate, the output quality won't be nearly as good as properly encoded H.264 or even MPEG-4 ASP.
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Old 27th September 2008, 00:45   #7  |  Link
laserfan
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Originally Posted by nm View Post
There are many similar MPEG-2 re-quantizers around, some even available as native Linux programs (Vamps, for example). They are fast, but with a DVB source and low target bitrate, the output quality won't be nearly as good as properly encoded H.264 or even MPEG-4 ASP.
I don't agree that there are "many similar" proggies to Super MPEG2 Transcoder for HD (in fact if I'd have found even one I'd likely have tried it) but I see now that I completely missed the OP's Linux requirement! Very hastily read the Subject and missed the meat!

If Vamps isn't up his alley, then the question is: what's the OP's playback method.

If it's a PC then x264 is the latest/greatest.
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Old 5th October 2008, 03:28   #8  |  Link
WalterK
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I'd say X264 for the video codec into avi, mp4 or mkv containers.
Whatever app ,frontend or script you decide to use is up to you.
If you are a GUI person then avidemux as for what settings for the encode using avidemux i couldn't really say.
If on the other hand you are comfortable with the cmdline then theres froggy1's H264enc script (search this section of the forums for more info) , it requires you have mencoder installed along with libx264, FAAC,mkvmerge (if you want to use the Matroska container) and MP4Box (if you wish to use the mp4 container) for the encode.
The great thing about H264enc is that it comes with several presets you can pick from not just ones that relate to video quality,for example if you plan to playback on a standalone player, PS3, Ipod etc. there are presets for those as well.
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Old 5th October 2008, 08:23   #9  |  Link
micmac
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Hello there,

I wrote a script for batch conversion to Xvid or x264 and AAC: Link. It's in Bash so it'll work for you. Maybe you want to give it a shot.

Regards
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Old 20th October 2008, 14:34   #10  |  Link
russellhq
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Thanks for all the tips guys.

I've finally started getting into the encoding after some computer issues


I've been using AviDemux with the x264 encoding option and am looking for ways to improve the video quality apart from basics like upping the bitrate etc


Any advice on filters and advanced encoding options would be mucho appreciated and save me many hours of trial and error :O

Also, not too worried about encoding speed as the Q6600 is a real workhorse
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