Lafras Henning wrote:
> Thanks Benny,
>
> My misunderstanding was assuming L145 if (snd_port->plc) - would be true
> but instead
> pj_bzero(output, size); is executed.
Yes. The default behavior is to send over zero frame to the sound
device if the stream doesn't return any frame (that is when
frame->type is NONE).
> In wav_writer.c and mem_capure.c the sound buffer is used without being
> zero'd regardless of the frame.type.
Frankly this could be a bug (see below). But even if frame.type is
NONE, the frame.size would (normally!) be zero too, so it's not a
major bug.
The effect of this bug is no silence would be written to the WAV
file, if the silence is expressed with frame.type=NONE rather than
zero frame, since when frame.type is NONE, the WAV writer won't
write any data to the file.
For now, or at least in pjsua, this bug does not manifest itself
since WAV writer is connected to the conference bridge which doesn't
emit NONE frame.
> Ignoring frame.type or zero-ing the buffer fixes the problem in my
> application, which is better though?
Zero-ing the buffer is better.
If you ignore frame.type (and instead only rely to frame.size to be
zero), there is a chance that you might miss some silence frames
like the WAV writer bug above.
> I see snd_port->plc is only created (depending on options options) when
> snd_port is created.
Yes.
> So do the codecs that don't have built-in PLC (g711 and gsm), rely on
> snd_port->plc? Or do they have their own plc?
gsm and g711 instantiate their own plc, separate than the plc in
snd_port. I used plc in snd_port mainly to experiment with plc
algorithm.
But looking at the gsm and g711 source codes again, it looks like by
default the plc is disabled too, since pjsip 0.7!
> Do I then need a PLC in my port at all?
No, you don't need plc. PLC should only be used in stream.c, since
once it gets over stream.c, there shouldn't be any frame lost!
regards,
-benny
> Regards
> Lafras
>
>
>
> ----- Original Message -----
> From: "Benny Prijono" <bennylp@xxxxxxxxx>
> To: "pjsip embedded/DSP SIP discussion" <pjsip at lists.pjsip.org>
> Sent: Tuesday, October 02, 2007 8:40 AM
> Subject: Re: [pjsip] How to handle silence / NONE frames?
>
>
>> Lafras Henning wrote:
>>> Hi Benny,
>>>
>>> In my application I get a scratching/clicking noise when the other side
>>> sends silence packets, On but on PJSUA no scratching occurs.
>>>
>>> My application is getting PJMEDIA_FRAME_TYPE_NONE frames during this
>>> silence,
>>>
>>> sound_port.c simply applies PLC to these packets, but surly there is a
>>> difference between missing and silence packets?
>>>
>>> What would you recomend?
>> There are two kind of PLCs in pjmedia, first is the PLC that comes
>> with the codec (such as Speex and iLBC), and the other is the
>> generic PLC that is used in sound_port.c and also by codecs that
>> don't have built-in PLC (g711 and gsm).
>>
>> The generic PLC is really bad, as it only replays the previous frame
>> (at lower intensity), and normally this creates the clicking noise.
>> So you should not use this. The sound_port.c also does not use this
>> by default either.
>>
>> So if you don't hear clicking noise in pjsua, could it probably
>> because pjsua uses Speex or iLBC (with their built-in PLC)?
>>
>> Indeed there is a different treatment for missing and silence
>> packets, this processing is done in stream.c, by looking at the
>> return status of the jitter buffer. The former will trigger the
>> codec's PLC, while the later won't.
>>
>> What kind of silence frames did you get?
>>
>> regards,
>> -benny
>>
>>
>>> Regards
>>> Lafras
>>>
>>> static pj_status_t zxTDM_put_frame( pjmedia_port *port,
>>> const pjmedia_frame *frame)
>>> {
>>> port_data *zxTDM = port->port_data.pdata;
>>> pj_int16_t *samples = frame->buf;
>>> unsigned i, count;
>>>
>>> if (zxTDM->Active!=1) return PJ_SUCCESS;
>>> if (zxTDM->Fifo==NULL) return PJ_SUCCESS;
>>> if (zxTDM->Fifo->Active!=1) return PJ_SUCCESS;
>>>
>>> if (frame->type != PJMEDIA_FRAME_TYPE_AUDIO)
>>> {
>>> pjsua_NonAudioFrames++;
>>> pjsua_NonAudioFramesType = frame->type; //yep getting 0
>>> return PJ_SUCCESS; //just ignor
>>> }
>>> /* Get number of samples */
>>> count = frame->size / 2 / port->info.channel_count;
>>> //It is possible to improve the performance of this critical section
>>> by bringing in the code from zxSimpleFifo and optimising it
>>> // to optimize similar to FifoBufferUnit- Calculate 2 blocks (upto
>>> end and from begining) that can be copied without testing - check
>>> PeekBuffer()
>>> for (i=0; i<count; ++i) {
>>> zxFifo_PostByte(&zxTDM->Fifo->Rx,pjmedia_linear2alaw(*samples));
>>> zxTDM->Fifo->Rx.TxCounter--;
>>> samples++;
>>> }
>>>
>>> //save data for PLC
>>>
>>> if (zxTDM->plc)
>>> pjmedia_plc_save(zxTDM->plc, (pj_int16_t*)frame->buf); //missing
>>> packets are fixed from the other side of the fifo.
>>>
>>> //NOW perform Echo cancelation //taken from sound_port.c
>>> if (zxpjsua_EchoCanceler) pjmedia_echo_playback(zxTDM->ec_state,
>>> (pj_int16_t*)frame->buf);
>>>
>>> return PJ_SUCCESS;
>>> }
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> Visit our blog: http://blog.pjsip.org
>>>
>>> pjsip mailing list
>>> pjsip at lists.pjsip.org
>>> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
>>
>> --
>> Benny Prijono
>> http://www.pjsip.org
>>
>>
>> _______________________________________________
>> Visit our blog: http://blog.pjsip.org
>>
>> pjsip mailing list
>> pjsip at lists.pjsip.org
>> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
>>
>
>
> _______________________________________________
> Visit our blog: http://blog.pjsip.org
>
> pjsip mailing list
> pjsip at lists.pjsip.org
> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
--
Benny Prijono
http://www.pjsip.org
