Avoiding time_increment_bits problem when encoding bad header MPEG4 videos to Ogg Theora
January 28th 2010

There is some debate going on lately about the migration of YouTube to HTML5, and whether they (i.e. YouTube's owner, Google) should support H.264 or Theora as standard codecs for the upcoming <video> tag. See, for example, how the FSF asks for support for Theora.

The thing is, I discovered x264 not so long ago, and I thought it was a "free version" of H.264. I began using it to reencode the medium-to-low quality videos I keep (e.g., movies and series). The resulting quality/file size ratio stunned me. I could reencode most material downloaded from e.g. p2p sources to 2/3 of their size, keeping the copy indistinguishable from the original with the bare eye.

However, after realizing that x264 is just a free implementation of the proprietary H.264 codec, and in the wake of the H.264/Theora debate, I decided to give Ogg Theora a go. I expected a fair competitor to H.264, although still noticeably behind in quality/size ratio. And that I found. I for one do not care if I need a 10% larger file to attain the same quality, if it means using free formats, so I decided to adopt Theora for everyday reencoding.

After three paragraphs of introduction, let's get to the point. Which is that reencoding some files with ffmpeg2theora I would get the following error:

% ffmpeg2theora -i example_video.avi -o output.ogg
[avi @ 0x22b7560]Something went wrong during header parsing, I will ignore it and try to continue anyway.
[NULL @ 0x22b87f0]hmm, seems the headers are not complete, trying to guess time_increment_bits
[NULL @ 0x22b87f0]my guess is 15 bits ;)
[NULL @ 0x22b87f0]looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag
Input #0, avi, from 'example_video.avi':
  Metadata:
    Title           : example_video.avi
  Duration: 00:44:46.18, start: 0.000000, bitrate: 1093 kb/s
    Stream #0.0: Video: mpeg4, yuv420p, 624x464, 23.98 tbr, 23.98 tbn, 23.98 tbc
    Stream #0.1: Audio: mp3, 48000 Hz, 2 channels, s16, 32 kb/s
  .

[mpeg4 @ 0x22b87f0]hmm, seems the headers are not complete, trying to guess time_increment_bits
[mpeg4 @ 0x22b87f0]my guess is 16 bits ;)
[mpeg4 @ 0x22b87f0]hmm, seems the headers are not complete, trying to guess time_increment_bits
[mpeg4 @ 0x22b87f0]my guess is 16 bits ;)
[mpeg4 @ 0x22b87f0]looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag
    Last message repeated 1 times
[mpeg4 @ 0x22b87f0]warning: first frame is no keyframe

I searched the web for solutions, but to no avail. Usually pasting literal errors in Google yields good results, but in this case I only found developer forums where this bug was discussed. What I haven't found is simple instructions on how to avoid it in practice.

Well, here it goes my simple solution: pass it through MEncoder first. Where the following fails:

% ffmpeg2theora -i input.avi -o output.ogg

the following succeeds:

% mencoder input.avi -ovc copy -oac copy -o filtered.avi
% ffmpeg2theora -i filtered.avi -o output.ogg

I guess that what happens is basically that mencoder takes the "raw" video data in input.avi and makes a copy into filtered.avi (which ends up being exactly the same video), building sane headers in the process.

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First impressions on a Neo FreeRunner
January 13th 2009

Yes, as the title implies, I am the fortunate owner of a Neo FreeRunner. For those not on the know, the NFR is a kind of mobile phone/PDA running free software, and aimed at being open, both from software and hardware perspective.

I bought it last week, and I already have things that I love, and others that I don't love that much. First thing that sucks: my 128kB Movistar SIM card is not supported, so I can't use the NFR to make calls! Apparently older versions of the SIM card are supported, so I will try to get hold of one (by the way, the simyo card I posted about some time ago works perfectly).

Another thing that is not so good is the stability of the software. However, I expected that, and I have no problem with it. Being open source, the software will evolve day by day, and I will love to see the evolution.

On the bright side: it is really great to be able to install different distros in your phone! I tried OpenMoko, FDOM, QtExtended (formerly Qtopia) and SHR, and all of them have good and bad things. It is like going back to when I tried different distros for my computers (now I mostly stick to Ubuntu or Debian). By the way, you can install Debian in the NFR (haven't tried it yet, because you have to install it in the microSD card, not in the main memory (it's too big for it). You can even try Google's Android, if you so wish.

But the really nice thing about it is that you can create your own apps for it. You can install Perl or Python interpreters, and then use the Command-line interface (yes, it does have command line) to run scripts. Or create icons on the desktop and link them to an action. For example, I created an icon that switches from portrait to landscape orientation when pressing it, and then back when pressing it again. I created another icon that launches mplayer when pressed, so I can watch a video in it by just pressing the icon.

I expect to blog more about the gadget, so stay tuned.

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Gmail and browser discrimination
June 4th 2008

Due to Iceweasel (Firefox) being so slow on my machine, I switched to Konqueror, which is reasonably fast and full of features, but nowhere as good as Iceweasel, I must say. However, IW is unbearable, so I'm waiting for FF 3.0 to use IW again.

I use an e-mail client to read my e-mail over IMAP, my main account being a Gmail one. However, I sometimes visit the Gmail site, for example to set it to fetch e-mail from some other accounts. I had always done it with IW, and everything worked fine, but now with Konqueror it doesn't.

With Konqueror I get the message:

and some features are missing (specifically, the option set how to fetch e-mail from other accounts, and some others).

I could understand it if Konqueror were missing some functionality/plugin that IW has and Gmail requires. But it is not the case. I can tell Konqueror to identify itself as Firefox, and THEN the Gmail page shows up correctly, so obviously it's not due to Konqueror's limitations. It sounds like a case of sloppy programming from the guys at Google, with something like:

if browser is one of 'IE', 'Firefox', 'Safari':
  show this page
else:
  show dumbed down page

After years of discrimination to non-IE users, and a tremendous fight to make webmasters produce standards-compliant sites, instead of specific browser-compliant ones, we still have to suffer this shit. And from Google, the "don't be evil" guys, supporters of free software and all that BS.

By the way, this issue is known, and mentioned, for example, in the Wikipedia page for Gmail.

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