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Video Transmission over UDP/CDC_NCM/USB on i.MX 6 Solo and L3.0.35_4.1.0_130816

Question asked by Ocean Jin on Jun 10, 2015
Latest reply on Jun 18, 2015 by Ocean Jin

Hi, I am currently developing an automotive embedded system based on i.MX 6 Solo chip and L3.0.35_4.1.0_130816_source.tar.gz

 

The application that I have been working on is Mirror Link.

 

Once a smartphone that has MirrorLink compliant is connected through an USB cable to the Head Unit, video and audio data are transferred from the phone to the unit.

 

The problem is that the video transfer throughput via RTP/UDP/IP/CDC_NCM/USB is somewhat slow.

 

MP4 files with low resolution are OK, but those with high resolution (1280x720p or above) are in poor conditions.

 

The TCP/UDP tuning parameters have been modified as follows.

 

net.core.rmem_default = 108544 -> 16777216 (default -> new)

net.core.rmem_max =     108544 -> 16777216

net.core.wmem_default = 108544 ->16777216

net.core.wmem_max =     108544 -> 16777216

net.core.optmem_max =   10240 -> 16777216

net.ipv4.tcp_mem =          5328    7104   10656

                                   -> 65536  131072  262144

net.ipv4.udp_mem =        5328    7104   10656

                                   -> 65536  131072  262144

net.ipv4.tcp_rmem =     4096   87380    227328

                                ->  8192   87380  16777216

net.ipv4.udp_rmem_min = 4096 -> 16384

net.ipv4.tcp_wmem =    4096   16384    227328

                                 ->  8192   87380  16777216

net.ipv4.udp_wmem_min = 4096 -> 16384

 

Could somebody verify that these numbers are reasonable, or suggest  any better buffer settings?

 

Thanks in advance.

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