[Gstreamer-openmax] Gstreamer Openmax plugins and Media demuxers

[Felipe Contreras]

On Thu, Aug 7, 2008 at 5:12 AM, gulshan karmani
<gulshan.karmani at gmail.com> wrote:
> Hi All,
>
>      I have some questions regarding Gstreamer Based Demuxers used
> inside poky for media playback,
>
> 1. While using  'avidemux'  as a demuxer plugin we get continuous
> 'Alignment Traps'
> which is affecting the audio quality. We have a cmdline option to tell
> the kernel to fix these traps and suppress the warning but this could
> be just a workaround.
>
> Is this alignment trap caused by demuxer ? Or we need to take care of something
> in lower layers ?
> Instead of avidemux if we use 'ffdemux_avi' we do not get these traps.
>
> [We use Gst-omx decoders below which are calling ffmpeg for decoding,
> ffmpeg has been hardware accelerated].
>
> 2. Which are the Stand-alone Aac and mp3 demuxers inside Gstreamer to be used ?
>
> We are trying to use ffdemux_mp3 for mp3 and getting some package
> building issues.
>
> While for Aac we tried gst faad but this is being identified as Aac
> decoder along with parser. Could we not use this plugin just as a
> demuxer ?
>
> Following chains are working for AAC :
> "gst-launch filesrc
> location=/media/sdmmc0p1/streams/bass47_1_ADTS_LTP.aac ! faad !
> alsasink"
>
> "gst-launch omx_filereadersrc
> file-name=/media/sdmmc0p1/streams/AAC_TestStreams/al09_44.aac !
> omx_aacdec ! omx_audiosink"
>
> While the ones which we want to use and not working are :
> "gst-launch filesrc
> location=/media/sdmmc0p1/streams/bass47_1_ADTS_LTP.aac ! omx_aacdec !
> alsasink"
>
> "gst-launch omx_filereadersrc
> file-name=/media/sdmmc0p1/streams/AAC_TestStreams/al09_44.aac !
> omx_aacdec ! alsasink"

Sorry for the late reply.

Normally GStreamer requires timestamps, and probably the alsasink is
expecting them. You can try with omx_aacdec use-timestamps=false, but
it would be better if you add an AAC parser before the decoder.

-- 
Felipe Contreras