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Falsehoods programmers believe about video

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11–20 of 139 posts

Re: Falsehoods programmers believe about video

#11
post #9

> a H.264 hardware decoder can decode all H.264 files and > video decoding is easily parallelizable At a previous job, I don't know if it was just the field I was in or just bad luck, but having to explain this over and over again was kind of a personal nightmare. That being said, this is an excellent list!

Curious - Why is this? Does this assume streaming video, and you can't look ahead in the stream? If you can jump ahead, it would seem to be easy to have multiple threads, starting at key frames to decode the content. You'd have to splice them together, but this seems possible.

1) You are now assuming that "seeking to a position will produce the same output as decoding to a position"; even if the video is well-formed (and you don't end up with massive issues where the key frames just don't work correctly) you are likely going to end up with subtle discontinuities between every segment. 2) You are now going to have to be buffering a couple seconds worth of uncompressed video somewhere, probably not on the GPU, leading to a much higher I/O bandwidth requirement somewhere that isn't good at that, so this is only probably going to be sort of parallel (FWIW, I believe most people who try to do parallel video decoding are assuming that they can have different parts of the encoder concentrate on different sections of the screen, which sounds good until you see how non-local video decoding can be).

Re: Falsehoods programmers believe about video

#12
post #5

Earlier quoted context omitted.

This unfortunately follows the conventions of the genre called "Falsehood programmers believe about X": http://spaceninja.com/2015/12/08/falsehoods-programmers-beli... I honestly think this genre is horrible and counterproductive, even though the writer's intentions are good. It gives no examples, no explanations, no guidelines for proper implementations - just a list of condescending gotchas, showing off the superio…

Managed to compile a list of these at: https://github.com/kdeldycke/awesome-falsehood#awesome-false...

Is this a real response to the parent post? As in, is your list curated to provide actual examples and meaningful tips, or is it just an even bigger pile of useless condescension?

Re: Falsehoods programmers believe about video

#13
post #11
post #9

Earlier quoted context omitted.

Curious - Why is this? Does this assume streaming video, and you can't look ahead in the stream? If you can jump ahead, it would seem to be easy to have multiple threads, starting at key frames to decode the content. You'd have to splice them together, but this seems possible.

1) You are now assuming that "seeking to a position will produce the same output as decoding to a position"; even if the video is well-formed (and you don't end up with massive issues where the key frames just don't work correctly) you are likely going to end up with subtle discontinuities between every segment. 2) You are now going to have to be buffering a couple seconds worth of uncompressed video somewhere, proba…

> 1) You are now assuming that "seeking to a position will produce the same output as decoding to a position"; even if the video is well-formed (and you don't end up with massive issues where the key frames just don't work correctly) you are likely going to end up with subtle discontinuities between every segment.

Wouldn't "the keyframes just don't work correctly" result in corrupted output anyway?

If we're worrying about already-broken situations then it is quite obvious that additional breakage may occur in related features.

Re: Falsehoods programmers believe about video

#15
- "all subtitle files are UTF-8 encoded"

Hah, this strikes really close to home. I've had to work with so so many subtile files in Eastern European and Turkish Windows codepages mostly but not entirely compatible with Win-1252. There's no way to tell them apart programmatically, so you check that the extended characters make sense. It's a bit of a nightmare.

Re: Falsehoods programmers believe about video

#16
post #13
post #11

Earlier quoted context omitted.

1) You are now assuming that "seeking to a position will produce the same output as decoding to a position"; even if the video is well-formed (and you don't end up with massive issues where the key frames just don't work correctly) you are likely going to end up with subtle discontinuities between every segment. 2) You are now going to have to be buffering a couple seconds worth of uncompressed video somewhere, proba…

> 1) You are now assuming that "seeking to a position will produce the same output as decoding to a position"; even if the video is well-formed (and you don't end up with massive issues where the key frames just don't work correctly) you are likely going to end up with subtle discontinuities between every segment. Wouldn't "the keyframes just don't work correctly" result in corrupted output anyway? If we're worrying…

I think the point is that video definitely is that broken and the only reason video does work is because everyone has work-arounds for everyone else's bugs. At least that's my experience with video. It's all a disaster.

Re: Falsehoods programmers believe about video

#17

Earlier quoted context omitted.

Managed to compile a list of these at: https://github.com/kdeldycke/awesome-falsehood#awesome-false...

Is this a real response to the parent post? As in, is your list curated to provide actual examples and meaningful tips, or is it just an even bigger pile of useless condescension?

[deleted]

Re: Falsehoods programmers believe about video

#18
The original one ( http://www.kalzumeus.com/2010/06/17/falsehoods-programmers-b... ) left me bafled. Then I realized you have to strike a balance; otherwise you cannot deal with names at all. The point where drawing the line depends on your industry/customers, but I'd safely say that it's too restrictive nowadays so these lists are useful somewhat and of course they are interesting.

Re: Falsehoods programmers believe about video

#20
post #5

Earlier quoted context omitted.

This unfortunately follows the conventions of the genre called "Falsehood programmers believe about X": http://spaceninja.com/2015/12/08/falsehoods-programmers-beli... I honestly think this genre is horrible and counterproductive, even though the writer's intentions are good. It gives no examples, no explanations, no guidelines for proper implementations - just a list of condescending gotchas, showing off the superio…

Perhaps there is scope for a list of Falsehoods Programmers Believe About Falsehoods Programmers Believe.

Let's start then:

1. Everything said in every "Falsehoods Programmers Believe..." list is true.

The Falsehoods sound like ultimate truths only because of the literary genre. They sound like they were written by an expert who not only knows what's true, but also knows what we think we know, which kind of automatically takes him/her to the next level of expertise.

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