Doom9's Forum - View Single Post - H.264 in AVI files

LoRd_MuldeR · 7th October 2011, 14:30

First of all: H.264 (MPEG-4 AVC) is more complex than MPEG-4 Part-2 (ASP). Multiple references, I-Frames and IDR-Frames, etc.

Also most of the problems with "AVI and H.264" do not originate from the AVI container itself, but form the way how AVI files commonly are created:
Through the antiquated VFW (Video for Windows) interface, as used by the still pretty popular VirtualDub(Mod).

For example, the x264 encoder uses a very long "lookahead", i.e. it reads like ~80 source frames, before the first (compressed) output frame is returned.
This hardly complies with the VFW concept of "one frame in, one frame out". Though hacks to workaround that problem have been invented...

(I think most MPEG-4 Part 2 simply didn't use a big "lookahead", so the problem was less striking)

Last but not least: I think putting MPEG-4 Part-2 into AVI never was the best idea, but it simply became the defacto-standard, back in the DivX ;-) era.
Putting H.264 into AVI is not a problem by itself either (if done properly!), but nowadays we have much better alternatives, such as MKV and MP4.

7th October 2011, 14:30	#2 \| Link
LoRd_MuldeR Software Developer Join Date: Jun 2005 Location: Last House on Slunk Street Posts: 13,248	First of all: H.264 (MPEG-4 AVC) is more complex than MPEG-4 Part-2 (ASP). Multiple references, I-Frames and IDR-Frames, etc. Also most of the problems with "AVI and H.264" do not originate from the AVI container itself, but form the way how AVI files commonly are created: Through the antiquated VFW (Video for Windows) interface, as used by the still pretty popular VirtualDub(Mod). For example, the x264 encoder uses a very long "lookahead", i.e. it reads like ~80 source frames, before the first (compressed) output frame is returned. This hardly complies with the VFW concept of "one frame in, one frame out". Though hacks to workaround that problem have been invented... (I think most MPEG-4 Part 2 simply didn't use a big "lookahead", so the problem was less striking) Last but not least: I think putting MPEG-4 Part-2 into AVI never was the best idea, but it simply became the defacto-standard, back in the DivX ;-) era. Putting H.264 into AVI is not a problem by itself either (if done properly!), but nowadays we have much better alternatives, such as MKV and MP4. __________________ Go to https://standforukraine.com/ to find legitimate Ukrainian Charities 🇺🇦✊ Last edited by LoRd_MuldeR; 7th October 2011 at 14:48.