On 17/04/2012 18:31, Jon Davies wrote:
I had a bug report relating to the ubuntu precise builds I've put together, the relevant bit of which is as follows:avconv version 0.8.1-4:0.8.1-0ubuntu1, Copyright (c) 2000-2011 the Libav developers built on Mar 22 2012 05:29:10 with gcc 4.6.3 Input #0, aac, from '/home/mark/Podcasts/Saturday_Drama/Saturday_Drama_-_Mountain_of_Light_b00sqgdw_default.partial.aac': Duration: 01:01:35.85, bitrate: 131 kb/s Stream #0.0: Audio: aac, 44100 Hz, stereo, s16, 131 kb/s Unrecognized option 'absf' Failed to set value 'aac_adtstoasc' for option 'absf' INFO: Command exit code 1 (raw code = 256)
I checked this Libav version on Debian Wheezy, and it works as before if avconv is invoked as "ffmpeg" (there is a wrapper installed). If invoked directly as "avconv", you get the warning above. I don't have Ubuntu Precise to hand at the moment, but I would expect it to work the same. If you can confirm this behaviour, would it work for the PPA build to call ffmpeg rather avconv, at least for the initial release?
it appears that recent versions of both ffmpeg and avconv have changed the options for applying bitstream filters (see http://ffmpeg.org/ffmpeg.html#toc-Bitstream-Filters).
That change has been around for a while, but up until now backwards compatibility has been maintained. This glitch happened last year with the "original" FFmpeg, but backwards compatibility was quickly restored. As of the last release (0.10.2), it still works as before (I think -absf is just converted to -bsf:a internally).
For ubuntu precise, due out in a matter of days, I'm going to have to change get_iplayer to support the new option formats, the question that arises is whether we should (a) change get_iplayer to support a more recent version of ffmpeg/avconv universally and drag windows, mac and older linux users into the new world, together with newer builds of the tools (b) treat this as a special case for ubuntu precise for now or (c) make it possible to support both the old and new option formats adding yet another option to get_iplayer to set this any thoughts? Jon
If the above suggestion doesn't work for you and you need to change get_iplayer, then I would say treat it as a special case for now. This is only a problem with the Libav fork, and only in their latest release 0.8.1, and thus is only an issue for Wheezy/Precise, and then only if you want to call "avconv". Before I get too far out on that limb: have other distros besides Debian/Ubuntu adopted Libav?
Since this breaking change has been pushed out in a release on a popular platform, get_iplayer will probably need to adapt eventually. Even if the "ffmpeg" wrapper provides a solution for Wheezy/Precise, it will eventually disappear. Besides, the original FFmpeg may ditch the old syntax at some point.
Since time is short, perhaps you could just branch get_iplayer and make the minimum changes required for Precise. We can go back and reconcile at a later date. I think we could lose the two-pass ffmpeg entirely (see below), but that seems like too much to bite off in the week or so before Precise is launched, as would trying to do an across-the-board upgrade of get_iplayer and tools.
Before changing get_iplayer, perhaps the place to start is to determine whether or not that filter is even necessary. It was put in to get around a problem with iTunes, but I recently checked that very thing in response to another thread. In the most recent version of iTunes the problem was no longer in evidence. I don't know if that is down to changes in get_iplayer, ffmpeg or iPlayer, but the problem is gone. If that observation holds up to further testing, I think it would be reasonable to simplify that bit of get_iplayer and tell users to update to the latest iTunes if necessary. There may be a few Leopard users unhappy at the news, but that's the breaks.
If we do need to retain the filter and update to using the new argument syntax, the version of ffmpeg installed with get_iplayer would need to be updated. It's still at 0.8, and I haven't bothered changing it since: a) there was no need; b) our source for builds (zeranoe.com) hasn't made any builds from the release branches since 0.8. It's no problem to update with the installer, but we would need to coordinate that change with the release of get_iplayer itself.
Perhaps a more future-proofed approach might to give get_iplayer the means to switch invocations of ffmpeg/avconv based on the name (ffmpeg vs. avconv). For the immediate future, we can probably assume that anything invoked as "ffmpeg" would accept the old syntax, and anything invoked as "avconv" would accept the new syntax. Seems kind of hack-ish, but it might be a reasonable brute-force solution.
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