Best pixel resolution to use when converting DVB-T to MPEG4

[Gentletouch]

My Humax machine captures TV at a resolution of 704 x 576. The image is anamorphic. When convering to MPEG4 in order to keep the aspect ratio correct I have to change the resolution, usually to something like 1024 x 576 or 704 x 396. As a beginner I do not know which of these options is best and why? Can anyone suggest which to use?

Regards

[Alex-Kid]

MPEG-4 (both ASP and AVC) can use 16:9 aspect ratio without resolution changing, just like MPEG-2 does.

[Blue_MiSfit]

I'd suggest leaving the resolution at 704x576 and setting the sample aspect ratio to 32:27 (which will give you 16x9 output)

[SeeMoreDigital]

I'd suggest leaving the resolution at 704x576 and setting the sample aspect ratio to 32:27 (which will give you 16x9 output)Actually, 32:27 is the (NTSC) 720x480 aspect ratio signalling value.... For (PAL) 704x576 try 16:11 or 64:45.


Cheers

[Gentletouch]

Ok. Thanks. I am using Xvid and have set the aspect ratio to 64:45, works great with my TV. Windows media player doesn't recognise the ratio and displays the file as 4:3. Can anyone suggest a video bit rate which will give the nearest quality to broadcast, without to big a file size. (These are TV recordings, each about 1hr long).

[yetanotherid]

Ok. Thanks. I am using Xvid and have set the aspect ratio to 64:45, works great with my TV. Windows media player doesn't recognise the ratio and displays the file as 4:3. Can anyone suggest a video bit rate which will give the nearest quality to broadcast, without to big a file size. (These are TV recordings, each about 1hr long).

Non-square (anamorphic) pixels aren't well supported by playback devices when using an AVI container (hence WMP getting it wrong). For better consistency it'd be better to encode using the x264 encoder and an MP4 or MKV container (if your playback device supports it). Plus for the same quality you should end up with smaller files.

Which program are you using for the encoding? Bitrate needs vary greatly from video to video for the same quality relative to the original.... it depends how hard they are to compress. Better to pick a quality rather than use a set bitrate (unless controlling the file size is a necessity).

[Gentletouch]

I am using AVIDemux for the encoding, The reason for the AVI container is that the files are intended for use with TVersity, DLNA media streaming sofware. TVersity doesn't seen to recognise other containers such as MP4. I shall try x264.

Regards

[yetanotherid]

x264 inside an AVI isn't a really good idea.... if AVIDemux will let you do it. Might be better to stick with XviD.

I'm not too familiar with AVIDemux but for encoding I'd set the XviD encoder for a constant quantiser, single pass encode, using a quantiser of 3 (or 2 for better quality). You'll have no control over the file size (it'll be whatever it needs to be to achieve the desired quality). If the file sizes start to get out of control try a quantiser of 4 and see if there's any noticeable drop in quality.

Personally, I'd be resizing down to square pixel dimensions as square pixel encodes with a width of 720 or less should be 100% compatible with any playback device. It might be a pity to encode a lot of video to find it doesn't display properly when you change playback devices at a later date. Can you see a quality drop when you do resize down, while watching the encode on your TV?
If you decide to go the square pixel route rather than select an aspect ratio, try using AutoGK to do the encoding. It does all the cropping and resizing etc automatically (you can manually select the video width) so it's virtually impossible to get the resizing wrong. AutoGK also has a single pass encoding mode which allows you to set the quality. The default is 75% which "I think" is equivalent to a constant quantiser of 2.7, which is supposed to be the optimum quality/file size setting for XviD. Anything over 75% and the quality barely increases (although you probably won't see an improvement at all) while the file sizes can start to increase dramatically.

I use AutoGK for all my XviD/AVI encodes. If the file sizes are too large I prefer to decrease the resolution rather than decrease the quality setting too much. I tend to use a width of 656 for 16:9 aspect ratio video and 640 for 3:4 aspect ratio. Dropping the resolution seems to make virtually no difference to the quality (compared with an encode using a width of 720) when both are running side by side on my monitors.

For anamorphic encodes I always use x264/MKV (using MeGUI as the encoder GUI).
Is this the software you're using? Are you steaming from a PC?
http://tversity.com/
It seems to support MP4 but it definitely supports MKV and seems to be able to play any format for which you have a directshow decoder installed. http://tversity.com/support/faq/
Do you have a directshow decoder such as ffdshow installed on your PC for decoding formats such as h264/MP4 etc?
Seems it also needs the Haali media splitter installed to play MKV files. http://tversity.com/download