[mythtv-users] MythTV streaming protocol takes 3x the bandwidth of CIFS streaming

[DarkNovaNick at gmail.com]

A couple months ago I started transcoding recordings to DIVX/MPEG-4/AVI  
using mythnuv2mkv, which allows me to do things that the built-in  
transcoder can't do, like deinterlace right in the transcoded recording, as  
one of my frontends is too slow to deinterlace the way I want on the fly.  
Sometimes this works fine, but on over half the recordings I experience a  
strange problem.

I'm streaming over a wifi link which has a maximum bandwidth of about 15  
Mbps. I was getting prebuffering pauses, so at first I thought the  
resulting file was peaking over the amount of bandwidth available, so I  
adjusted the mencoder parameters in the script to limit the maximum  
bandwidth to 6 Mbps (using vrc_maxrate and vrc_buf_size). I still got  
prebuffering pauses, so I used Linux's "iftop" utility to monitor the  
bandwidth mythfrontend was actually using. Even though the file itself was  
less than 6 Mbps, mythfrontend was maxing out my wifi link at 15 Mbps and  
wanting more bandwidth, hence the prebuffering pauses.

Next I created a CIFS/Samba map from the frontend's recordings directory to  
that on the backend, so that when I play back the recording it uses the  
CIFS share instead of MythTV's internal streaming protocol. Now the same  
recording works fine, and if I view the bandwidth used with "iftop" it  
shows around 6 Mbps, which is correct.

The strange thing is, I can have one show recorded which works just fine  
with MythTV's streaming protocol, only using the appropriate amount of  
bandwidth, and then the show right after it where everything about the  
source should be the same tries to max out the wireless. I cannot identify  
any differences that would cause this. The file itself is the same bitrate.

Does anyone have any ideas? This is on MythTV 0.23.1+fixes26437-0ubuntu1.

Nick
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