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Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

marco.org

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Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#51
post #26

Earlier quoted context omitted.

iPhone storage and cellular bandwidth are still extremely expensive. Over $100 for a measly 16gb of storage or 4gb of LTE.

Is 16GB really that measly when it comes to podcasts? Even at, say, 128MB per hour (!) you've got over 100 hours of capacity there. Enough for a full waking week, nonstop.

People with 16 GB iPhones really struggle with running out of storage. Some may be lucky to fit one 128 MB podcast on their phone.

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#52
post #7

That's not the only reason. We have been podcasting for over 10 years, and early on we tried to use VBR MP3s because we are teach people who know about that sort of thing. As it turns out, not everyone is listening using a modern device. When we tried VBR a significant number of people could not listen because their MP3 playing hardware/software of choice did not support VBR files properly. They didn't realize this w…

My favorite bug about this was on an _ancient_ MP3 player I had (an EigerMan F20), which supported VBR MP3s...incompletely. It didn't support decoding regions with certain bitrates, so it would just silently skip them, leading to extreme confusion on my part.

I had a similar problem and never considered that...

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#53
post #7

That's not the only reason. We have been podcasting for over 10 years, and early on we tried to use VBR MP3s because we are teach people who know about that sort of thing. As it turns out, not everyone is listening using a modern device. When we tried VBR a significant number of people could not listen because their MP3 playing hardware/software of choice did not support VBR files properly. They didn't realize this w…

I've had problems with hardware players that couldn't handle 320kbps blocks of VBR. Restricting the max bitrate fixed the issue but most encoders don't expose this as an option (lame does).

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#54
Not a fan of VBR MP3 files in general. They're more complicated to deal with when writing a codec, due in no small part to the seeking problem. And VBR is one of those optimizations that only works on things that didn't need optimizing in the first place (i.e., low-entropy frames.) There's just not much point to it.

If you need VBR MP3 for some reason, chances are you really need a better format.

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#55

If you want more context to this, there's a lot more in the most recent ATP podcast (with timestamp link included in the article). Which kind of highlights a problem that I think is only going to grow over time - the general greatness of podcasts has one big black spot in that they're tough to share. I've seen so many discussions recently where there was awesome additional context or info in a recent podcast, but it…

I like podcasts, but they're unnerving to me. It's too much time wasted to get to the point. And as opposed to music, I can't program properly when listening to them Not to mention a lot of podcasters act in a radio way (which make sense for radio), with repetitions, talking slowly, endless introductions, chit chat, etc

2x playback speed helps a lot I find.

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#56

If you want more context to this, there's a lot more in the most recent ATP podcast (with timestamp link included in the article). Which kind of highlights a problem that I think is only going to grow over time - the general greatness of podcasts has one big black spot in that they're tough to share. I've seen so many discussions recently where there was awesome additional context or info in a recent podcast, but it…

I just don't understand why Marco has bitten so hard into this problem. It doesn't matter at all . Everybody skips the ATP theme song anyway, and VBR will only negligibly improve quality of the rest of the show ( as Marco himself has pointed out ). And it's not like the theme song sounds bad in its current state! I have never noticed any artifacts or flaws in the recording at all. This is almost literally only someth…

It's not just improving the quality of the theme song, it's decreasing the size of podcasts. A 10-20% reduction in bandwidth costs isn't anything to sneeze at, especially for larger distributors like relay.fm etc.

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#57

If you want more context to this, there's a lot more in the most recent ATP podcast (with timestamp link included in the article). Which kind of highlights a problem that I think is only going to grow over time - the general greatness of podcasts has one big black spot in that they're tough to share. I've seen so many discussions recently where there was awesome additional context or info in a recent podcast, but it…

I just don't understand why Marco has bitten so hard into this problem. It doesn't matter at all . Everybody skips the ATP theme song anyway, and VBR will only negligibly improve quality of the rest of the show ( as Marco himself has pointed out ). And it's not like the theme song sounds bad in its current state! I have never noticed any artifacts or flaws in the recording at all. This is almost literally only someth…

[deleted]

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#58
post #44
post #29

There are many degrees of VBR MP3 seeking support, and it's often surprisingly bad. In the case of Firefox's element, it was very poor (nearly unusable in my testing) until a few months ago: https://bugzilla.mozilla.org/show_bug.cgi?id=994561 https://bugzilla.mozilla.org/show_bug.cgi?id=1163667 I had a fun time testing different js audio players, and going though their many confused bug reports, issues and threads al…

You're correct about that there are different degrees of seeking support. Seeking VBR MP3 with perfect accuracy is trivial by forward-reading. However, this is obviously highly inefficient on long duration seeks. For instant seeking support, you need to (partly) depend on the optional VBR headers. This comes with its own set of issues, e.g., the most commonly used Xing header contains only 100 seek table entries, whi…

> However, this is obviously highly inefficient on long duration seeks.

Is it that bad? On the podcast, Marco claimed that seeking forward through an MP3 to find the correct time is pretty efficient, and that the reason for all this trouble is that streaming (specifically, requesting the correct byte offset from the server, if you want to jump to a specific time on the stream) is the problem he's trying to tackle here. He said that if it weren't for the streaming use case, he'd be fine with forward-reading.

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#59
post #26

Earlier quoted context omitted.

VBR have been the red-headed step-child of MP3 since the beginning. I have no idea why, maybe it was difficult to write good encoders and decoders for it for back in the day. The few times I used them, I found trivial space savings compared to a CBR and to be honest I thought I could hear a difference (maybe its not humanly possible if the implementation of the encoder/decoder is good but what if the implementation i…

iPhone storage and cellular bandwidth are still extremely expensive. Over $100 for a measly 16gb of storage or 4gb of LTE.

It's completely absurd when a 64GB microSD card is less than $20.

https://www.amazon.com/SanDisk-microSDXC-Standard-Packaging-...

Re: Why don’t podcasts use VBR MP3s? Because iOS and macOS don’t accurately seek them

#60
post #48
post #7

That's not the only reason. We have been podcasting for over 10 years, and early on we tried to use VBR MP3s because we are teach people who know about that sort of thing. As it turns out, not everyone is listening using a modern device. When we tried VBR a significant number of people could not listen because their MP3 playing hardware/software of choice did not support VBR files properly. They didn't realize this w…

And audio data is relatively small that the savings aren't that valuable.

That's not true. In the ATP episode Marvo mentioned he wanted the theme song or clips to be able to sound really good (192 or 256kbps stereo) but their normal talking was nearly perfect at 96 mono.

Then add in all the gaps in people's speech where you need almost no data and he said he got pretty good savings.

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