Audio-only issues with BBC content via get_iplayer

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chewitt
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Audio-only issues with BBC content via get_iplayer

Postby chewitt » Mon Apr 26, 2010 1:57 pm

Hello folks,

I'm downloading content from the BBC website using an OSX front-end GUI app (Get iPlayer Automator) for the fairly well known get_iplayer script. The script is retrieving the flash streams from the BBC using flvstreamer (or RTMPdump?) and then converting the resulting flv file to H.264 mp4 using ffmpeg. This has been working great for a long while, until recently when the BBC tweaked the stream format. I'm now downloading content that plays back okay (audio and video) on my OSx 10.6.3 laptop, but plays audio-only (no video) if the content is moved to an AppleTV box for playback. The active H.264 codec on the ATV is Perian 1.1.4 acquired by installing aTVflash. The developer of Get iPlayer Automator has passed on the following explanation of what the BBC has done:

"What has happened is they now encode the 1280x720 stream as 1280×724 with 4 lines of bottom crop which should bring it back to 1280×720. The problem is, many players don’t understand the bottom crop directive. VLC and Adobe Media Player/Flash play it correctly. The Quicktime included in 10.6.3 plays it with a green line 4 pixels tall at the bottom. The Quicktime pre-10.6.3 and the version currently in the Apple TV refuse to play the video altogether. There is no real solution other than to hope everyone gets their players to support the bottom crop tag. That or completely re-encode every video. Note: This is not a problem with the flv-mp4 conversion."


The streams I've been downloading are 832x468, but it's the same issue. It's not clear to me whether this is a problem with the QuickTime player on the ATV, or with Perian as the active H.264 codec. This is my first foray into understanding what Perian really does so I'm a bit clueless, please excuse me if I'm not describing things right.

Are you generally aware of this issue and is it something you can shed some light upon?

Christian
Last edited by chewitt on Thu Apr 29, 2010 2:09 pm, edited 1 time in total.

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chewitt
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Re: Audio-only issues with BBC content via get_iplayer

Postby chewitt » Wed Apr 28, 2010 3:57 am

No replies? ..I know I mentioned the dirty word 'AppleTV' but the same behaviour affects Perian playback on OSX 10.5.x too

Mr VacBob
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Re: Audio-only issues with BBC content via get_iplayer

Postby Mr VacBob » Fri Apr 30, 2010 12:51 am

Does it work with 10.5 without Perian?

Either way, I'd need to see a file.

Also, there is no such thing as a "bottom crop tag", so I can't tell what the actual problem is from that description.

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chewitt
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Re: Audio-only issues with BBC content via get_iplayer

Postby chewitt » Mon May 03, 2010 3:15 am

I've uploaded a file here http://rapidshare.com/files/382526870/maps.zip that contains two video files from the beeb's 720p stream (a program about maps) which was 1280x720 until they did something to the format. They now come down as 1280x724 and won't play back on an ATV with/without perian 1.1.4/1.2.1 installed. The files are:

a) Original FLV as downloaded by get_iplayer
b) MP4 container that get_iplayer has converted the FLV to using the following ffmpeg command

ffmpeg -i input.flv -vcodec copy -acodec copy -f ??? -y output.mp4 ..I've not been able to figure out the ??? from looking at the get_iplayer code

I've installed OSX 10.5.0 server in VMware Fusion and tested OSX 10.5.0 with Quicktime 7.2.1, no perian and it plays (jerky, but it has video) so what I've been told about this being related to <10.6.3 'quicktime' (presumably meaning 7.6.6) aren't right. If I install perian 1.1.4 into the VM image it still plays okay, so this prob. isn't a perian issue.

Does anyone know what version of Quicktime is on an AppleTV (3.latest) ??

In short, I'm stuck and struggling to identify what the problem with these video files is, and thus where to start looking for a solution. Any light you can shed on the issue from having a look at the video files I've posted would be a HUGE help..

Christian

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Re: Audio-only issues with BBC content via get_iplayer

Postby gbooker » Mon May 03, 2010 4:44 am

chewitt wrote:Does anyone know what version of Quicktime is on an AppleTV (3.latest) ??

According to /System/Library/Frameworks/QuickTime.framework/Versions/A/Resources/Info.plist:
7.1.8
OS is closest to 10.4.9


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