Comment by jsmthrowaway | Hacker News Reader

Comment by jsmthrowaway | Hacker News Reader

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The solution is AAC, regarding which a number of prominent podcasters introduced FUD several years ago and now the podcasting industry is reluctant to give up MP3 -- unlike pretty much every other audio-related industry in the world. Seriously, MP3 was on its way out the year the Backstreet Boys released that song, and it surprises me that people still stick to it despite the VBR thing being a shitty problem in software that long. None of the solutions that Marco found are great, either. The solutions were dismissed decades ago in manners like this:

http://www.foobar2000.org/FAQ#why_is_seeking_so_slow_while_p...

Here's an example of podcasters talking each other out of AAC:

http://podcastingguru.com/aac/

His is not the first article I've read conflating "AAC" with some kind of "Enhanced Podcast" buzzword and then dismissing it based on the flaws of "Enhanced Podcasting." I left the radio industry in 2006 and we'd already transitioned all in-house production and delivery away from MP3 then. Probably 50% of the spots we received from external shops in 2006 were MP3.

At some point you have to sit down with your listener and say that MP3 player you bought at Target in 2001 is holding us back, man. Marco is wrong on this one: it's AAC that would deliver all the good things that he wants, not VBR MP3. Fun fact: all AAC is VBR, in a manner of speaking, and it's way better than the hack that is VBR MP3s.

The problem with AAC is in the container format, as Marco explains in his podcast: While some important metadata like chapter marks which a podcast player might want to display are within the first KB in an MP3 file, this same information is interleaved somewhere in the stream in AAC.

Which means that you can't have all features when streaming an AAC file, in a time when streaming podcasts is getting more popular every day. You first have to download the whole file before you can display e.g. chapter information.

Of course you could just embed that information in the RSS feed, but you could do the same with jump tables for VBR MP3s. So AAC does not solve all your problems, you just get a different set of problems.

No, this is incorrect. It's up to the implementation of the muxer to determine where index information goes, which is typically at the end of the file. This is simply because writing a file is a single pass operation, and you don't know the contents of the atom until you've gone through the all the data for each stream. Many muxers provide an option to place it at the beginning of the file by adding padding and overwriting it afterward, which solves the progressive streaming problem.

Weren't they talking about .mov files at the time?

The MP4 container was based on the Quicktime file format (.mov).

Thanks! Makes sense.

Those are all problems with a specific, objectively crappy container, as you've noted. There are many alternative containers and no reason the podcasting community couldn't come up with its own, such as by extending Matroska. This obviously creates separate problems, but I'd like to see the podcasting community start to shape its own destiny a bit rather than expect others to innovate for them or kludge older formats to do things they weren't supposed to do.

Why not a podcasting specific container that handles streaming and fixed cases, includes support for all the novel stuff podcasters want to do, and so on? Container development is one of the easier parts of multimedia, and there's too much thinking around a specific codec being tied to a specific container (just like your comment). Legacy support is of course the big elephant in the room, but I'd venture a well-founded guess that the average podcast listener is listening on a device that supports apps. (Maybe I'm wrong.)

I can't think of a single good container format. They're all rubbish. Even Matroska is arcane and very poorly documented, and suffers from the end goals and types of media it is used for being encoded in the design. Containers are a giant space in which to innovate and have been that way for years. Unfortunately, open source multimedia development is largely tied up by a certain group of people with a certain background and very specific use cases in mind.

That context from the podcast would have been awesome in this piece. Why wasn't it there?

One of the OP's requirements is that this work in iTunes, which precludes making a new container format.

I also think existing containers would meet the requirements - for example, Ogg meets the requirement of both being storable and easily streamable. Also, the Matroska spec is being updated to a new version, and being standardized in the IETF CELLAR working group. I'd highly suggest participating if you'd like to help improve both the format and the specification.

Codec Encoding for LossLess Archiving and Realtime transmission (cellar) documents: https://datatracker.ietf.org/wg/cellar/documents/

Matroska draft: https://datatracker.ietf.org/doc/draft-lhomme-cellar-matrosk...

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