is H264 on AVI a hack?

[synnchan]

I love the x264 codec and I use it to record my games. I'd like to keep using it, but I read on several places people saying it's a "hack" even though it works for me. When I record the videos, I leave the settings like this:



I read that leaving it on "Single pass - lossless" and "Zero Latency" checked, fixes the "hack" problem. But I'd like to know you guys' opinion on it. Are those settings ok? or should I change something?

[hello_hello]

It is but so is Xvid in an AVI if it uses B-Frames. That's the problem.... the VFW system works on a one frame in, one frame out basis, and I don't think the AVI container has the ability to store information regarding the type of frames. When B-Frames are used the frame display order and the encoding/storage order might be different, so I think for AVC it's the same as Xvid. To get around the problem frames are packed together as a single frame or several frames have to be decoded before any can be displayed, causing a slight delay. The hacks are well supported though, especially for mpeg4 (Xvid, Divx etc). I don't know about AVC as I've not used it in an AVI for anything but an intermediate file for re-encoding on occasion.

The ultra fast preset doesn't use B-Frames so I assume the ultra fast preset on it's own would be enough to avoid any hackery. I'm not sure about the lossless mode. I don't think it uses B-Frames but I'm not certain.

Are you stuck with using the VFW version of x264 for a reason, or forced to use AVI rather than a more modern container such as MP4 or MKV? Playback support for h264 in an AVI is well supported on a PC but it's probably somewhat uncommon for standalone hardware players.

[sneaker]

Like hello_hello said, it is kind of a hack but without b frames you are mostly safe.

Your options:
1. switch "Output mode" from "VFW" to "File". This will write to an extra file without AVI but VirtualDub will still create a dummy (or audio-only) AVI file. So you need to mux the video file and the audio-only avi back together later using e.g. mkvmerge.
2. switch to using the https://forum.videohelp.com/threads/367446-Virtualdub-External-Encoder-feature feature of VirtualDub. It supports encoding and muxing without AVI but is more difficult to set up initially. Since you are talking about capturing: I don't know if it possible to use it with VirtualDub capture mode.
3. continue using the hack. If it works for you .. why not?

The ultra fast preset doesn't use B-Frames so I assume the ultra fast preset on it's own would be enough to avoid any hackery. I'm not sure about the lossless mode. I don't think it uses B-Frames but I'm not certain.

x264 lossless does indeed not use b frames.

[El Heggunte]

AFAIK, only MPEG-4 ASP (DivX, Xvid) may use "packed bitstream". AFAIK, there is no "packed bitstream" for H.264 video in an AVI container (probably because nobody wanted to implement the idea ).

H.264 video in AVI is, essentially, the same thing as H.264 video in a transport stream. For the VfW "interface" (so to speak), the problem now is not only the B-frames, but also the multiple reference frames, the B-pyramids, etc. But the ancient and obsolete Video-for-Windows is not the only way to access an AVI file. Windows Media Player itself does not use VfW, except as a "last resort". Both MPC-HC and MPC-BE use DirectShow for dealing with AVI files. Also, keep in mind that the ASF container (pseudo-renamed to "WMV" by Microsoft) is just a glorified AVI, and is as unsuitable as AVI for storing video formats that use B-frames

http://forum.doom9.org/showthread.php?t=120407

http://forum.doom9.org/showthread.php?p=1523574#post1523574

[shekh]

The word "hack" does not mean it is bad. The order of frames in AVI must be extracted from avc stream. So what? There is enough software that does it.
The "VirtuaDub hack" option is another story (extension for delayed output from codec) and is not just for VirtualDub, any program may implement it. If it works use it.

[hello_hello]

I wasn't sure if "packed bitstream" had ever been implemented for AVC in an AVI. Thanks for the info El Heggunte. It's good to know for certain it hasn't.

[hello_hello]

The word "hack" does not mean it is bad. The order of frames in AVI must be extracted from avc stream. So what? There is enough software that does it.

I'd agree in principle. I have lots of AVIs with Xvid encoded video and packed bitstreams. Hardware player support is so universal it's almost hard to think of it as being a hack any more.... it's just how it works..... but not so much for AVC in an AVI. If you're only ever going to be using a PC for playback it doesn't matter too much, but still.... even if I was writing AVC to an AVI file when encoding I'd probably want to remux it as an MP4 or MKV at some stage so it can be played using a device that isn't a PC.

[shekh]

I suspect OP is using it as intermediate anyway.

[synnchan]

So... from what I gather, if I use x264's lossless mode I will be safe?

[poisondeathray]

So... from what I gather, if I use x264's lossless mode I will be safe?

not necessarily ; it depends on how it's going to be used and what programs

By default, x264's lossless mode --qp 0 (or --crf 0) uses long gop with b-frames to increase compression . So that will lead to the same problems with decoding in susceptible programs ( green frames, black frames, out of order frames, out of sync...) . Some programs will have no problems

Also, many programs cannot decode AVC lossless mode properly

Using all I-frames (instead of long gop) will make out of order decoding less likely in AVI container . But that will significantly reduce compression efficiency .

Some people suggest disabling b-frames, but even p-frames can cause problems in some programs (e.g. vegas) with out of order decoding (mixed up frames). You can find many threads on this on various forums.

[Cornucopia]

...Also, keep in mind that the ASF container (pseudo-renamed to "WMV" by Microsoft) is just a glorified AVI, and is as unsuitable as AVI for storing video formats that use B-frames

Not quite true. Whatever it's faults, ASF/WMV is a completely reworked container format and uses both extensible GUID headers/metadata and DOES fully support B-frames. It was built with streaming in mind (in answer to RealMedia), which makes use of extended runs of B-frames. Couldn't say whether multi-reference or pyramid features are there, though.

Of course, for best use of AVC & HEVC, I'd suggest using MP4 or MKV containers, both of which have much more thorough & robust support for complex codecs than AVI (as well as better modern player support).

Scott

[sneaker]

By default, x264's lossless mode --qp 0 (or --crf 0) uses long gop with b-frames to increase compression.

It does? My tests say it doesn't use b frames at all. Please re-check.

[poisondeathray]

By default, x264's lossless mode --qp 0 (or --crf 0) uses long gop with b-frames to increase compression.

It does? My tests say it doesn't use b frames at all. Please re-check.

You're right, I,P only in lossless mode . For both CLI and VFW

[synnchan]

Okay guys, so this is what I did:

1) Capture the game in VFW H264 - Superfast preset (beause Ultrafast fails on certain games) - Keep/Accept only RGB - Single pass lossless - Zero Latency checked.

2) Drag and Drop the .avi into VirtualDub - use the Resize Filter to increase the video's resolution by 8x - Select x264vfw as video compression method (select Convert to YUV 4:2:0 under x264vfw configuration instead of RGB so the video will play everywhere) - Save as AVI.

3) Drag and Drop the new .avi into Avidemux - Select "Copy" as Video Output - Select "AAC (Faac)" as Audio Output - Select "MP4 Muxer" as Output Format - Save the .mp4.

And that's all. Since the final video will be stored into .mp4 instead of .avi, will things be fine then?

P.S. Here is a video showing my whole process step by step: https://www.youtube.com/watch?v=6LI9HmzNBdA

[poisondeathray]

Yes, remuxing it into a suitable container will fix the problems associated with AVC in AVI, but not all programs or devices accept lossless AVC. So it still depends on how you 're going to be using it

[El Heggunte]

...Also, keep in mind that the ASF container (pseudo-renamed to "WMV" by Microsoft) is just a glorified AVI, and is as unsuitable as AVI for storing video formats that use B-frames

Not quite true. Whatever it's faults, ASF/WMV is a completely reworked container format and uses both extensible GUID headers/metadata and DOES fully support B-frames. It was built with streaming in mind (in answer to RealMedia), which makes use of extended runs of B-frames. Couldn't say whether multi-reference or pyramid features are there, though.

Of course, for best use of AVC & HEVC, I'd suggest using MP4 or MKV containers, both of which have much more thorough & robust support for complex codecs than AVI (as well as better modern player support).

Scott

Hmmmm, some moons ago, a Doom9 moderator, namely foxyshadis, wrote more or less the same things you said here today. But apparently he forgot to stress that the full features of the ASF container were defined only for the second version of the ASF specification... which almost nobody uses — with Micro$oft themselves not being the exception to the rule.

P.S.:

When I was at Microsoft we made an official decision not to support H.264 in ASF as ASF was not a friendly container for content where the display and decode order was different. Even supporting B-frames in VC-1 for ASF was quite the hack.

That was a primary reason why Smooth Streaming used fMP4 from the get-go instead of ASF.

source: http://forum.doom9.org/showthread.php?p=1654802#post1654802

[synnchan]

Just to clarify: if a program/device/whatever doesn't support it, the video won't even play at all, right? or will it still play but bugged/glitched or something?

[poisondeathray]

Just to clarify: if a program/device/whatever doesn't support it, the video won't even play at all, right? or will it still play but bugged/glitched or something?

Yes, it won't even play if it's not supported