> 1. AV sync is taken care by StageFright. on video playback, once a frame arrives back after decoding, AVSync logic (audio-video timestamp check) is handled here http://git.omapzoom.org/?p=platform/frameworks/base.git;a=blob;f=media/libstagefright/AwesomePlayer.cpp;h=e58535cc4d470a617adf16dd95e5f8435c36a5e7;hb=refs/heads/p-froyo#l1054
On Fri, Jan 28, 2011 at 8:13 AM, <[email protected]> wrote: > 1. AV sync is taken care by StageFright. > > 2. Qcom does implement audio OMX which uses hardware acceleration. > They are not open sourced yet and also it depends on which chipset you are > talking about. On snapdragon they all are software decoders, which uses SF > software codecs. > > 3. Android provides the entire framework for playback, these OMX > decoders are just to enable hardware acceleration. Remaining parsing, AV > sync, time stamp etc., are taken care by the framework. > > > > Hope this helps. > > > > From: [email protected] > [mailto:[email protected]] On Behalf Of ?? > Sent: Friday, January 28, 2011 7:16 AM > To: Deva R > Cc: [email protected] > Subject: Re: [android-porting] why samsung and qcom do not implement audio > omx section in /hardware > > > > thank you Deva, > > so, in your opinion h/w video omx decoder and s/w audio decoder can > work together, since they work in two independent threads, i agree with > you. > > > > here is place that confuses me: as to the synchronization of a/v, do we > need to do something else, or only rely on stagefright to control the a/v > pace. > > > > > > 2011/1/28 Deva R <[email protected]> > >> ps: >> also, i have review the code of ti in android_root/hardware/ti/omp3, >> they >> do have audio decoders such as aac, mp3, wma etc, >> from normal logical, we should implement video and audio omx component >> together, so we can play movie in full omx way. > > video codecs are not listed as mostly they will run in DSP side or a > h/w accelerated subsystem, which wont be part of android code. > and during av playback, there will 2 handles active (each to decode > audio/video bit streams) > as long as we have a omx handle to talk to,bridged to > hardware/software codec, android can go ahead with playback. > > ps. > complete releases can be found in www.git.omapzoom.org projects > >> i wonder why they(samsung and qcom) do not implement the audio omx >> section, >> however, they have video omx's implementation. >> here is my guess: >> 1. they do not implement audio decoder, but only using the audio decoder >> originally in Android >> 2. they implement their own audio codec as the same way of Android's audio >> codec, then substitute them, >> 3. they have other implementations of decoding audio that we do not know > > probably they use s/w codecs only (which comes by default with > stagefright/opencore) > with current generation mobile processors, decoding aac/mp3 in arm > side is feasible and not that of an overhead. > > also, there may be implementations which are not public, where h/w > accelerated audio codecs are integrated. > > On Thu, Jan 27, 2011 at 10:15 PM, 王川 <[email protected]> wrote: >> hi group, >> i'm working on implementation of vendor omx section in froyo, and >> make >> it run together with stagefright. >> i notice that in android_root/hardware/qcom/media folder there are qcom's >> implementations. >> also i checked out samsung's omx code (from >> git://github.com/codeworkx/android_device_samsung_galaxys.git), in which >> there is also no audio omx component section. >> i wonder why they(samsung and qcom) do not implement the audio omx >> section, >> however, they have video omx's implementation. >> here is my guess: >> 1. they do not implement audio decoder, but only using the audio decoder >> originally in Android >> 2. they implement their own audio codec as the same way of Android's audio >> codec, then substitute them, >> 3. they have other implementations of decoding audio that we do not know >> can anyone give me some ideas? and what is your strategy of audio decoder, >> omx way or using android's internal audio decoder >> >> ps: >> also, i have review the code of ti in android_root/hardware/ti/omp3, >> they >> do have audio decoders such as aac, mp3, wma etc, >> from normal logical, we should implement video and audio omx component >> together, so we can play movie in full omx way. >> my question is: why qcom and samsung do not implement audio omx but only >> video omx component? and what audio decoder do they use when playing >> movie? >> >> >> > >> -- >> unsubscribe: [email protected] >> website: http://groups.google.com/group/android-porting >> > > > > -- > Regards, > Deva > www.bittoggler.com > > > > -- > > unsubscribe: [email protected] > website: http://groups.google.com/group/android-porting > > Please do not print this email unless it is absolutely necessary. > > The information contained in this electronic message and any attachments to > this message are intended for the exclusive use of the addressee(s) and may > contain proprietary, confidential or privileged information. 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