Avi Demux - what settings should I use when converting to avi?

[Digmen1]

I use AviDemux to convert my files from wmv, mp4 and mkv to avi.

I like to retain the original size and quality.

What settings do you suggest I use or play with.

Sometimes the file sizes vary hugely from the original. Is this OK?

[Baldrick]

Are you converting to avi with mpeg4-asp xvid? If so then try increase the constant quantizer a bit for lower file size. Click on configure under video to adjust the xvid properties.

[Digmen1]

Thanks Baldrick but two things

1 I can't find those settings you mentioned. I looked under Preferences and Video.

2 I just converted two wmv files to avi and they came out 50 percent larger in file size. The quality looks good. Should I just accept this or should I try to find a way to make them smaller, I do want to keep the quality.

[hello_hello]

I can't tell you how to change settings in AVIDemux as I've not used it, but basically you're recompressing the video, and as no two videos recompress by the same amount at the same quality, the output files sizes can vary quite a bit, even if the source videos are the same size. Much of the difference could also be due to recompressing the audio, depending on the encoder and settings being used there.

Maybe give ffcoder a shot. It's fairly easy to use and converts to and from lots of formats. If you choose AVI as the File Format and Xvid as the encoder, click on the Config button for Xvid and in the window which opens, load the default settings. Change the "Mode" to "Constant Quantizer". A quanitzer value of 2.0 is maximum quality. Higher values lower the quality and reduce the file size. Most people use between 2.0 and 3.0, but experiment to see what suits.
You'd change xvid's settings in pretty much the same way when using AVIDemux, but I don't know how to open the xvid configuration using it. Baldrick indicated there's a configure button under the video section.

If you want to aim for a particular file size using ffcoder, leave the Xvid encoder set up in Constant Quantizer mode, check the "Target MB" box in ffcoder's main window and select your desired file size. ffcoder will automatically run a 2 pass encode for you. Keep in mind though, when selecting a file size you're going about it in kind of the "opposite" way. You'll know what the file size will be, but not the quality.

[Digmen1]

@hello hello
Thanks for that, I am just starting to get a grip on video coding etc.

@Baldrick - I found the Video Configure's ! - its under the Video Copy/Convert button on the left hand panel.
I was losing in the more traditional top menus.

Now I am going to use 2 passes for all my conversions, it takes longer, but seems to give better quality

[hello_hello]

Now I am going to use 2 passes for all my conversions, it takes longer, but seems to give better quality

In theory xvid's single pass encoding isn't true quality based encoding whereas 2 pass is, but at a high enough quality setting single pass is pretty good.

As an experiment try running a single pass encode using a quantizer between 2 and 3. When it's done, note the file size, then use that file size for a 2 pass encode. The 2 pass encode will be encoded "differently" but if you run the two encodes side by side I doubt the 2 pass version will stand-out in terms of quality. If you try it, let us know if you see any major difference.

Mind you xvid has had it's day anyway. If quality is the priority you might consider using the x264 encoder instead. Using the same encoder settings it encodes the same way regardless of whether you use 2 pass or single pass encoding, assuming the resulting file sizes are identical for each. As a result single pass x264 encoding is more the "norm" these days.

[Digmen1]

@hello hello
As I said above I am a bit of a novice with video codecs etc, I try to keep up, but it is so complicated.

Anyway, I like my file sot be avi, so I will check to see if x264 is avi.

When I read up on the wikihow on avidemux, it said that with two pass encoding, the first pass it basically reads each frame etc, so that when it does the second pass it know how to encode it.

[hello_hello]

Anyway, I like my file sot be avi, so I will check to see if x264 is avi.

You can put x264 video in an AVI container but it's not really ideal and could cause problems. Generally an MP4 or MKV container is used.
AVI, MP4 and MKV are containers which can contain various types of audio and video etc. You can put the same video and audio in an MKV file as you can store in an AVI. MKV is basically the new AVI, only it's a lot more versatile.

The x264 encoder is a newer type of mpeg4 encoder. Xvid is an mpeg4 part 2 encoder, while x264 is an mpeg4 part 10 encoder. http://en.wikipedia.org/wiki/MPEG-4#MPEG-4_Parts
Old DVD/AVI capable players generally only support mpeg4 part2. Pretty much all current devices support mpeg4 part 10 including Bluray players.

The x264 encoder is much better than xvid. It'll compress to an equal quality using smaller file sizes but it's much better at retaining detail than xvid. To be honest you're probably "learning" using a format which is becoming obsolete. Not that you won't be able to play your xvid/AVI files for years to come, but the x264 encoder has become the "standard".

When I read up on the wikihow on avidemux, it said that with two pass encoding, the first pass it basically reads each frame etc, so that when it does the second pass it know how to encode it.

Yep, that's how it works. Xvid's single pass encoding is basically "dumb" encoding. In theory, 2 pass will allow it to distribute the bits better for more consistent quality, but using a high enough quality setting (bitrate) you'll probably not see a difference either way. The x264 encoder, on the other hand, can use the same method for single pass encoding as it does for 2 pass encoding. Both methods perform quality based encoding. If you run a single pass encode using a specific quality setting, then use the resulting file size for a 2 pass encode, the end result will be virtually the same. With a decent CPU, x264's single pass encoding can be faster than encoding using 2 passes with xvid and for a given file size the quality will be better (that may be a reason why your re-encodes are larger in size than the original).

Anyway, unless you particularly need to use xvid/AVI for some reason (hardware player compatibility), I'd consider switching formats. Even in the torrent world, AVI is slowly going the way of the Dodo. Outside of Apple devices, MKV/MP4 support is fairly standard these days (Apple devices generally support MP4).

[Digmen1]

@Hello Hello

Thanks for your very detailed reply.

I am a bit of an eccentric I suppose, and I tend to do things outside the normal.

I play most of my files on my Windows PC.

Years ago I got lots of avi, wmv, mov and asf and now flv files.

I liked to play them on VLC player or Classic Media player.

I found that avi files nearly always played well and you could fast forward them etc etc.
The other formats often crashed or would not fast forward.
So I started converting them to avs and they play well.

But as you say, so many new files are in Mp4 or Mpv, that I am fighting a losing battle, trying to convert them.

So I will so a bit of study and see if they play in my Media Classic player, and if they do I may stop trying to convert them, and just convert the old wmv, asf and mov files.

Thanks once again

[hello_hello]

I pretty much always use my PC for playback too, so file type isn't such a major concern, but there's a few different types of media players in this house and they're all happy with MKV, so that's what I use. Mainly because when it comes to remuxing files, there's really no MP4 or AVI equivalent to MKVMergeGUI in terms of ease of use (muxing is the process of changing the container format without converting the video or audio, or taking individual video and audio streams and saving them as a single file, whether it be AVI or MP4 or MKV etc). When it comes to extracting individual streams from files, MKVCleaver is very easy to use.

Are you referring to Media Player Classic or Media Player Classic Home Cinema? If it's the former it's old and outdated. If it's the latter it looks pretty much the same as the old MPC only it has more features and it's updated regularly. It'll play all the common video format's "out of the box" without the need for external codecs or splitters, and it'll definitely play MKVs and MP4s. It's the player I prefer to use. It also supports DXVA (hardware decoding) so if your video card supports it, MPC-HC will use the video card to decode the video rather than the CPU. Support for h264 decoding is pretty standard now. Most cards produced in the last five years or so can do it. For xvid/AVI.... chances are you'll have to keep using the CPU.