[Speex-dev] Problems with the Speex Jitter Buffer

[David Feurle]

Hi,

I am using the JitterBuffer. Since there is not so much documentation I 
think I dont use it in a correct way. All the packets are recieved (I 
control the sequence numbers) but the JitterBuffer often tells me he has 
no packet. I am using it in the following way:

I am not sure if I use the ticks correctly but I think it can be set to 
20(msec).
It is set as a Member in my class and i pointed out where i use it so it 
is clear if i use it somewhere i better shouldnt.

- I initialize the JitterBuffer with ticks = 20 (saved in the variable 
m_Ticks)
- My network thread repeadedly (every 20msec) calls AddPacket() which 
adds the packet to the buffer
          320 bytes of audio data are set as the data
          the timestamp is set to the sequence number of the packet 
times 20 (m_Ticks)
          the span of the packet is set to 20 (the packet covers one 
tick entirely)
- A thread which plays my Audio calls every 20msec the function GetSound()

As I said before the buffer just returns more or less the halve of the 
packets. But all the packets are added to the JitterBuffer.
I posted some of the code i use in my email and i would be really 
thankfull if anybody could tell me where i am using the JitterBuffer wrong.

Many thanks in advance

David Feurle



Init()
{
    m_JitterBuffer = jitter_buffer_init(m_Ticks);
    jitter_buffer_reset(m_JitterBuffer);
}

Exit()
{
        jitter_buffer_destroy(m_JitterBuffer);
}

void BeatJitterBuffer::AddPacket(Packet* packet)
{
    m_Mutex.Aquire();
   
        char buff[320];
        JitterBufferPacket p;
        m_Decoder->DecompressPacket(packet, buff, 320);
        p.data = buff;
        p.len = 320;
        p.timestamp = packet->SequenceNumber() * m_Ticks;
        p.span = m_Ticks;
        jitter_buffer_put(m_JitterBuffer, &p);
    }

    m_Mutex.Release();
    delete packet;
}

 void BeatJitterBuffer::GetSound(char* buffer, size_t maxLength)
{
    int ret;

    if (320 == maxLength)
    {
        JitterBufferPacket packet;
        packet.data = buffer;

        m_Mutex.Aquire();

        ret = jitter_buffer_get(m_JitterBuffer, &packet, 0);

        if(ret != JITTER_BUFFER_OK)
        {
            ZeroMemory(packet.data, maxLength);
         }

        jitter_buffer_tick(m_JitterBuffer);
        jitter_buffer_update_delay(m_JitterBuffer, &packet, NULL);
        m_Mutex.Release();
    }
    else
    {
        ZeroMemory(buffer, maxLength);
    }
}