[mythtv] 0.18.2, IOBOUND, ringbuf, and Live TV Jitter

[Lutz Mändle]

Hi,
sometimes ago I played around with the following settings in 
RingBuffer.cpp to have better result using mythfrontend via 54Mbit 
wireless LAN.

//#define TFW_DEF_BUF_SIZE (2*1024*1024)
//#define TFW_MAX_WRITE_SIZE (TFW_DEF_BUF_SIZE / 4)
//#define TFW_MIN_WRITE_SIZE (TFW_DEF_BUF_SIZE / 8)
#define TFW_DEF_BUF_SIZE (64*1024*1024)
#define TFW_MAX_WRITE_SIZE (TFW_DEF_BUF_SIZE / 4)
#define TFW_MIN_WRITE_SIZE (TFW_DEF_BUF_SIZE / 128)

The comment lines are the original settings, with these new settings 
I've got good results for recorded programs, but Live-TV had the old 
behaviour.

After searching the code I've found this in tv_rec.cpp:

void TVRec::SetupRingBuffer(QString &path, long long &filesize,
                            long long &fillamount, bool pip)
{
    ispip = pip;
    filesize = gContext->GetNumSetting("BufferSize", 5);
    fillamount = gContext->GetNumSetting("MaxBufferFill", 50);

    path = gContext->GetSetting("LiveBufferDir") + QString("/ringbuf%1.nuv")
                                                       
.arg(m_capturecardnum);

    outputFilename = path;

    filesize = filesize * 1024 * 1024 * 1024;
    fillamount = fillamount * 1024 * 1024;

    rbuffer = new RingBuffer(path, filesize, fillamount);
    rbuffer->SetWriteBufferMinWriteSize(1);   //<<- these line is now 
commented out
}

After commenting out the last line in this function, Live-TV over 
wireless LAN works reasonable.

Maybe  this helps.

Und Tschüß...
Lutz Mändle         Internet: lmaendle at gmx.net
Berlin/Germany