Hi Vignesh, On Thu, Jul 7, 2016 at 2:44 PM, Vignesh Venkatasubramanian < vigneshv-at-google....@ffmpeg.org> wrote:
> On Wed, Jul 6, 2016 at 4:50 PM, Vignesh Venkatasubramanian > <vigne...@google.com> wrote: > > On Fri, Jul 1, 2016 at 3:03 PM, Ronald S. Bultje <rsbul...@gmail.com> > wrote: > >> Hi, > >> > >> On Fri, Jul 1, 2016 at 5:27 PM, Vignesh Venkatasubramanian < > >> vigneshv-at-google....@ffmpeg.org> wrote: > >> > >>> On Fri, Jul 1, 2016 at 12:48 PM, Ronald S. Bultje <rsbul...@gmail.com> > >>> wrote: > >>> > Hi, > >>> > > >>> > On Fri, Jul 1, 2016 at 3:29 PM, Ronald S. Bultje <rsbul...@gmail.com > > > >>> wrote: > >>> > > >>> >> Hi, > >>> >> > >>> >> On Fri, Jul 1, 2016 at 3:12 PM, Vignesh Venkatasubramanian < > >>> >> vigneshv-at-google....@ffmpeg.org> wrote: > >>> >> > >>> >>> On Fri, Jul 1, 2016 at 11:06 AM, James Almer <jamr...@gmail.com> > >>> wrote: > >>> >>> > On 7/1/2016 2:53 PM, Ronald S. Bultje wrote: > >>> >>> >> Hi, > >>> >>> >> > >>> >>> >> On Fri, Jul 1, 2016 at 1:40 PM, James Zern < > >>> >>> jzern-at-google....@ffmpeg.org> > >>> >>> >> wrote: > >>> >>> >> > >>> >>> >>> On Fri, Jul 1, 2016 at 10:07 AM, Carl Eugen Hoyos < > >>> ceho...@ag.or.at> > >>> >>> >>> wrote: > >>> >>> >>>>> Do we have decoder support (for either vp8 or vp9) for these > >>> files? > >>> >>> >>>> > >>> >>> >>>> No, only encoding and muxing. > >>> >>> >>> > >>> >>> >>> Seems like a feature request, but no reason to block this one > if > >>> the > >>> >>> >>> vp8 one is here. > >>> >>> >> > >>> >>> >> > >>> >>> >> I'm not sure I have an opinion on this... But it feels strange > to > >>> allow > >>> >>> >> encoding of content we cannot decode. Being ffmpeg, how do we > >>> recommend > >>> >>> >> people handle the files created with this feature, if not by > using > >>> >>> ffmpeg > >>> >>> >> itself? > >>> >>> > >>> >>> One plausible reason is that Chrome can decode this. So it will be > >>> >>> useful for people who already have ffmpeg in their pipelines and > want > >>> >>> to create such files. And like James Almer mentioned, this isn't a > >>> >>> first. VP8 Alpha has been this way too. > >>> >> > >>> >> > >>> >> The fact that something is the way it is, does not prove that it is > >>> >> therefore right, or that we should therefore continue doing it that > way > >>> in > >>> >> other cases. > >>> >> > >>> >> So you're suggesting that it is perfectly fine for people to use > Chrome > >>> as > >>> >> decoder if FFmpeg is the encoder. What if people don't have Chrome > >>> >> installed? Or what if they want a way of UI-less batch-processing > such > >>> >> files, e.g. what if a service like Youtube/Vimeo wants to allow > upload > >>> of > >>> >> vp8a/vp9a files without invoking Chrome for decoding? > >>> >> > >>> > > >>> > Additional evidence in [1], [2]. > >>> > > >>> > There absolutely seems to be interest in support for vp8a/vp9a > decoding > >>> > outside Chrome. I'm not saying you should implement it in all > multimedia > >>> > frameworks ever created in human history, but doing it in one of them > >>> (e.g. > >>> > ffmpeg, since it already supports encoding) certainly sounds helpful? > >>> > > >>> > >>> I'm not saying alpha decoder shouldn't ever be implemented in ffmpeg. > >>> I'm just saying that it shouldn't be a reason to block this patch. :) > >>> Sorry if i wasn't clear before. > >> > >> > >> I totally understand that you would think that, since it means you don't > >> have to do anything :). > >> > >> But there's an issue with this thinking. We're essentially already the > >> dumping ground for anything multimedia-related nowadays. After all, we > >> maintain it and keep it working (assuming basic tests), things couldn't > get > >> much easier than that, right? But is it actually useful to anyone? I > mean > >> not just useful for you, but useful to a wider set of people, at least > in > >> theory. > >> > >> If there's no decoder, I would claim that the wider utility of this > thing > >> is essentially zero. And that's somewhat of a concern. > >> > >> So, how do we get a decoder? vp8a suggests that just waiting for one to > >> spontaneously combust out of thin air just doesn't work. So I'm > suggesting > >> you provide us with one. It's ok if it uses libvpx instead of ffvp8/9. > >> Since vp8a encoding is already in, I won't ask for a vp8a decoder > either. > >> I'm just asking for a vp9a decoder. It might even be OK if it's > implemented > >> on top of ffmpeg instead of inside libavcodec (I'm not sure how others > feel > >> about this), i.e. just something that invokes libavformat to parse a > webm > >> file, create two decoders to get the yuv and a planes, and then merge > them > >> together into a yuva420p picture. I'm just asking for something _small_ > and > >> _simple_ (i.e. not "Chrome") that we can point users to when they ask > "how > >> do I decode vp9a files". > >> > >> I asked on IRC (#ffmpeg-devel) and several people concurred: > >> > >> <BBB> jamrial: so … I’m looking for a second opinion here, like, an > >> independent one… am I being too hard on these guys for saying “an > encoder > >> needs a decoder”? > >> <JEEB> BBB: I do tend to agree that in general it goes dec->enc, or > both at > >> the same time. be it a fully lavc decoder or just utilizing a decoder > >> library > >> <jamrial> BBB: no, you're not being hard > >> > >> So it seems I'm not entirely alone in this opinion within the ffmpeg > >> developer community. > >> > > > > Alright, i have a working patch for the decoder locally (i will push > > that to the ML shortly). > > Here it is: http://ffmpeg.org/pipermail/ffmpeg-devel/2016-July/196403.html Thanks, that resolves my concerns. Ronald _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel