Does USB interface have a bitrate threshold?

firstrig

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Dec 17, 2013
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A lot of media devices like HDTVs, Blueray players, AV receivers feature USB as an input interface which allows people to plug their external hard drives and play movies from them. Does this interface maintain the integrity of the audio in its full glory (true 5.1/ DTS / dolby digital) or do they downsample it to basic stereo?

Basically, will I lose audio quality if I load my movie onto my hard disk as opposed to playing the same movie from a Blyeray disk?

Also, does it have a video bitrate threshold? If I have uncompressed Blueray at 50Mb/sec, is the USB interface fast enough to relay all that data to the player without stuttering or downsampling it?
 
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Hi,

No it does not, but that doesn't mean a whole lot.

USB is a...


Hi,

No it does not, but that doesn't mean a whole lot.

USB is a packetized digital interface, it just transfers data from the host to a target device on the bus or from a device to the host; it does not care what that data is, how much data is delivered, or how fast that data is delivered. There are established upper limits on performance but very few (if any) established lower limits on performance. Performance of USB devices is all over the map. Some mass storage devices may perform suitably well to meet the needs of certain real time applications such as video and audio playback while others may fall short. Most modern USB host and device controllers are good enough to support playback of full HD video with HD audio but this hasn't always been the case.
Devices such as Smart TVs, BluRay Players, and AV Receivers have embedded operating systems which can understand the filesystem on a block storage device attached over USB (such as a USB thumbstick). They read a file from the USB stick and decode the contents in the exact same way that a media player application on your PC would read a file from your hard disk drive. The application reads a bit, decodes it, buffers what it hopes is enough to account for variations in read throughput, and begins playback. If the buffer runs dry, playback will pause briefly until the device can catch up.
 
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