- From: Robert O'Callahan <robert@ocallahan.org>
- Date: Fri, 30 Mar 2012 09:37:13 +1300
- To: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
- Cc: Chris Rogers <crogers@google.com>, "Wei, James" <james.wei@intel.com>, "public-audio@w3.org" <public-audio@w3.org>, public-webrtc@w3.org
- Message-ID: <CAOp6jLbxWUc98ZKHyZ6bf8xDcvM3-kcXqtg76aqRW87Y=eQV5w@mail.gmail.com>
On Fri, Mar 30, 2012 at 1:43 AM, Jussi Kalliokoski < jussi.kalliokoski@gmail.com> wrote: > I have some use cases in mind, for example a DAW might be rendering > content to a file, let's say there's a following graph: > > Media Input -> Processing Worker (reverb, etc) -> Encoder Worker > > The desired behavior is that if the stream is stalled, it won't output > anything to avoid waiting for input from being written to the file, but if > the stream is drained, wait until the effects produce just silence, and > then signal the encoder to stop recording. > That is an interesting use-case. It can be solved with the existing spec: set autoFinish to false on your processing Worker, so that it keeps going when all inputs have finished. In your processing Worker, you will get onprocessmedia callbacks with no inputs, and it can keep producing output. Once you know that you won't ever produce anything but silence, the processing Worker should call finish() on its ProcessMediaEvent to end its stream. I think that's quite a natural solution. There are a couple of problems with it. One is that you'd like to be able to finish at a particular sample, and the current API doesn't have a way to do that. Probably the finish() method should take a time parameter. The other problem is that we really need two kinds of "autoFinish": one attribute that lets the Worker control whether it finishes as soon as all inputs are removed, and another attribute that lets the page control whether the Worker finishes automatically or not. In your example, some users of the Worker might want it to keep producing silence indefinitely while there are no inputs, e.g. because they expect to attach new inputs later. Probably the best approach is to have an autoFinish attribute on the ProcessMediaEvent for Worker-side control, in addition to autoFinish on the stream. Thanks, Rob -- “You have heard that it was said, ‘Love your neighbor and hate your enemy.’ But I tell you, love your enemies and pray for those who persecute you, that you may be children of your Father in heaven. ... If you love those who love you, what reward will you get? Are not even the tax collectors doing that? And if you greet only your own people, what are you doing more than others?" [Matthew 5:43-47]
Received on Thursday, 29 March 2012 20:37:44 UTC