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Author
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Topic: Direct Play/PlayWhileIngest on Dolby Servers?
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Carsten Kurz
Film God
Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009
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posted 10-20-2014 01:47 PM
Yes, the limitations are a bit strange, but some may be historical. Doremis will only do it from network sources, that have been setup and qualified for live play in the ingest manager. The rational behind this was probably that no 'raw' distribution data should be played, but only content that had been pre-ingested and verified on another Doremi or TMS. Sony R320 will only PlayWhileIngest from network folders through FTP and obviously assume an LMS/TMS as the source. R510/515 do not yet support that feature. Dolby supporting it from CRU seems that they believe the necessary data rate can be supported by CRU/SATA (which is true). Both Doremi and Dolbys have only USB2.0 ports, so PlayWhileIngest is out of the question over these ports. Same for GDC.
Typical data rates for DCPs during live play is around 25-35MByte/s. Todays drives support this without a problem, if they are okay and do not suffer from drive degradation. But it's not possible over USB2.0.
There is always a risc to do this, since the content being read from the disc has not been pre-verified for integrity, and distribution drives can have all sorts of issues, bad sectors, etc. Still I think that most drives will probably perform okay, at least if a large buffer of a couple of minutes is used. I know a small theater playing their arthouse series (one screening per week) direct from distribution drives on their GDC. Seems that so far they are doing fine. The issue, however, is that especially art house features arrive on USB/notebook drives very often nowadays, and only the most recent servers support USB3.0.
- Carsten
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Carsten Kurz
Film God
Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009
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posted 10-20-2014 08:52 PM
That is true, but distribution drives, if done properly, will usually not be used like this, but always be formatted before copying, or even with sector-copying applied. The largest amount of data on DCP drives are the MXF files, these are usually few, but very large files. So, with commercial DCP drives, fragmenting shouldn't occur.
However, unlike common interleaved video/audio files, DCPs need access to at least 2 separate files during playout - video and audio mxf. But again, todays drives with transfer rates of 100+ Mbytes/s and large caches will usually cope with that.
I brought up this thread specifically because festivals regularly have two technical issues - little time to prepare/ingest features, and not enough space on the server RAIDs to have all the festival content ingested at the same time.
Then again, a lot of festival content arrives on USB drives, but USB3.0 is used more and more. But with CRU or eSATA chances for PlayWhileIngest or DirectPlay would be better.
- Carsten
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