Remuxing get_iplayer downloads to play on my TV

[Andy Bircumshaw]

On 20 April 2012, at 12:56, Steve Champion wrote:
> … the conversion … takes a long time... presumably because I am not merely remuxing, but doing a conversion. I'm struggling a bit to understand the subtleties of video/audio formats.

Y'know, I think you're doing alright. 

You questions seem to indicate you understand the difference between remuxing and transcoding, which is the big divide, really.

I really like this explanation of codec vs. container: http://html5.xoofoo.org/video.html

Reading that might make you feel more confident about knowing you know this stuff. The article talks about video used on the web and the current HTML standards, but the principles of codecs and containers are universal to video files.

> So, my question is:
> 
> 1) Based on this table, is there a format that my TV can play which requires only a remux (of what get_iplayer downloads) rather than a conversion?

I don't think so. 

I'm not sure if this table is up to date, but it'll give you an idea: http://beebhack.wikia.com/wiki/IPlayer_TV

You might try the WMV versions, but I wouldn't bet on it.

The best encoding widely in use at the moment is h264. Your telly doesn't support that. 

I think the best quality formats that your telly supports are Xvid and MPEG-4.

I'm confused about the relationship between DivX and MPEG-4. It's not clear to me whether your telly will play DivX-encoded movies.

I think best bet is to download with get_iplayer at the highest resolution and then transcode a copy to watchable format. This will inherently always result in lower video quality. You may be able to minimised the quality loss by choosing a slower transcode (2- or 3-pass) or by utilising larger file sizes. 

MPEG-II is the format used in DVDs. I believe it's a lower quality than Xvid / MPEG-4, but it may be relatively fast to transcode. You might get adequate video quality by choosing MPEG2 and larger file sizes, however beware that even iPlayer's "HD" streams can be a bit blocky with artefacts on occasion. 

Transcoding is never ideal. You'll have to experiment a bit and see what works for you, see if you can get a compromise - of file-size / render time / image quality - that you're happy with.

iPlayer uses the "current standard" of h264, so you might consider buying something like the PlayOn HD Mini or the Western Digital TV Live which are HDMI-connected players and which handle this format. They're small, quiet and they have a dedicated h264 decoder chip, so they'll handle HD video just fine; it looks like they're now going for as little as £50 or £60. 

> 2) If this is the case, what would be the ffmpeg command line to do the required remux? Given that, I could make a batch file to remux at will [that much I _could_ handle :-)  ]


I don't use ffmpeg that much, I'll let someone else help, unless you get really stuck.

aB.