[vlc-devel] Opus RTP raw audio decoder plugin patch

[Yupeng Chang]

Hi,
Thanks for your advice!

Could you tell me where I can get some documents about VLC architecture?
I am not quite clear how dmuxer is connected to packetizer and then
connected to decoder.

Thank you!

Yupeng Chang
Dec-02-2013


On 1 December 2013 18:00, Ilkka Ollakka <ileoo at videolan.org> wrote:

> On Fri, Nov 29, 2013 at 07:11:02PM +0800, Yupeng Chang wrote:
> > Hi Ilkka,
>
> Hi,
>
> > Thanks for your advice.
>
> > I did a little dig on the opus.c decoder, and I found the only thing this
> > decoder needs, to decode Opus raw data, is an OggOpus header.
> > And there is a function opus_write_header in opus_header.c, which can
> make
> > one OggOpus header for me, so I just added one header to make it work.
>
> I would prefer this change to be other way around, so you change
> decoding function so it takes raw opus in and packetizer strips ogg
> header if present. Would be much cleaner for future in mind.
>
> It wouldn't be as small change, but I would prefer it that way.
>
> > Please help to review again.
> > Thanks very much!
>
> > Yupeng Chang
> > Nov-29-2013
>
>
> > On 28 November 2013 20:48, Ilkka Ollakka <ileoo at videolan.org> wrote:
>
>
> > > Hi,
>
> > > Thanks for the new patch.
>
> > > Why not use multistream api (OggOpus uses it) ? I don't have clear idea
> > > how they differ (than that basic decoder seems to output S16N and
> > > multistream can output FL32). Maybe someone more into Opus can clarify
> > > this?
>
> > > On Thu, Nov 28, 2013 at 08:24:11PM +0800, Yupeng Chang wrote:
> > > > From 49da1c8c17b763cf71ee65e1b9f925ccc4e7b79f Mon Sep 17 00:00:00
> 2001
> > > > From: Yupeng Chang <ypchang at ambarella.com>
> > > > Date: Thu, 28 Nov 2013 20:19:17 +0800
> > > > Subject: [PATCH 2/2] codec: Add Opus raw decoding.
>
> > > > +    written = opus_decode(p_sys->p_raw_dec,
> > > > +                          data, size,
> > > > +                          (opus_int16*)p_aout_buffer->p_buffer,
> > > > +                          buf_size / nb_channels, 0) * nb_channels
> * 2;
> > > > +
> > > > +    p_aout_buffer->i_nb_samples = nb_samples;
> > > > +    p_aout_buffer->i_pts = date_Get( &p_sys->end_date );
> > > > +    p_aout_buffer->i_length = written;
>
> > > I think it would be clearer if you would do the multiplication when you
> > > set i_lenght, not directly to opus_decode return value.
>
> > > --
> > > Ilkka Ollakka
> > > Everybody is somebody else's weirdo.
> > >                 -- Dykstra
>
> > > _______________________________________________
> > > vlc-devel mailing list
> > > To unsubscribe or modify your subscription options:
> > > https://mailman.videolan.org/listinfo/vlc-devel
>
>
>
> > From f1c2ceb4f443551efff6714e055a55e3e2b502de Mon Sep 17 00:00:00 2001
> > From: Yupeng Chang <ypchang at gmail.com>
> > Date: Thu, 28 Nov 2013 20:19:03 +0800
> > Subject: [PATCH 1/2] access: Enable Opus RTP.
>
> > ---
> >  modules/access/live555.cpp | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
>
> > diff --git a/modules/access/live555.cpp b/modules/access/live555.cpp
> > index 824cdf2..84dcba8 100644
> > --- a/modules/access/live555.cpp
> > +++ b/modules/access/live555.cpp
> > @@ -980,6 +980,16 @@ static int SessionsSetup( demux_t *p_demux )
> >                      else
> >                          msg_Warn( p_demux,"Missing or unsupported
> vorbis header." );
> >                  }
> > +                else if( !strcmp( sub->codecName(), "OPUS") )
> > +                {
> > +                    tk->fmt.i_codec = VLC_CODEC_OPUS;
> > +                    if( sub->rtpTimestampFrequency() )
> > +                        tk->fmt.audio.i_rate =
> sub->rtpTimestampFrequency();
> > +                    {
> > +                        msg_Warn( p_demux, "Using 48kHz as default
> sample rate." );
> > +                        tk->fmt.audio.i_rate = 48000;
> > +                    }
> > +                }
> >              }
> >              else if( !strcmp( sub->mediumName(), "video" ) )
> >              {
> --
> Ilkka Ollakka
> The good thing about standards is that there are so many to choose from.
>                 -- Andrew S. Tanenbaum
>
> _______________________________________________
> vlc-devel mailing list
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>
>
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