0

Dropout of audio

Devans

April 21, 2010 00:15

None

Follow

I have a 720p video playing on a 410. We have had some audio dropout issues. It began with no pattern, but yesterday someone experienced a dropout at the same place three times in a row. Are there any things I should look for that you can think of? I am thinking vbr data rate and card integrity to begin with.

• Facebook
• Twitter
• LinkedIn

4 comments

• 0
  
  RokuLyndon April 21, 2010 01:30

  
  
  IN the past, I've only noticed dropouts when the flash card wasn't fast enough to keep up with the needed throughput. Also, if the bitrate of the video is too high, then that could cause problems for the card. How high is your bitrate?
  
  We normally recommend a max of 25Mbps, although there are cases when you can go higher. And, for that bitrate, your carde throughput should be 4Mbps minimum, but more comfortably 6Mbps.
  
  For the brightsign shell, you can type readperf filename, to test the card and see what it's throughput is.
  
• 0
  
  Devans April 21, 2010 02:30

  
  
  Lyndon,
  
  We are using Transend SDHC 4GB cards rated at 20Mbps (SD 3.0 SPD Class 10).
  The video is encoded VBR, so that may be a problem. I'm reading the bitrate at 18.97 with a limit at 25. I thought we were using 30Mbps cards.
  
  Here is a reading from Streamclip:
  
  Stream: HistorySlideshow.ts
  
  Type: MPEG transport stream
  
  Duration: 0:02:22
  Data Size: 322.80 MB
  Bit Rate: 18.97 Mbps
  
  Video Tracks:
  4096 MPEG-2, 1920 × 1080, 16:9, 29.97 fps, 25.00 Mbps, progressive
  
  Audio Tracks:
  4098 MP2 stereo, 48 kHz, 384 kbps
  
  Stream Files:
  HistorySlideshow.ts (322.80 MB)
  
  
  I made a new render:
  
  Stream: HistorySlideshow.ts
  Path: /Volumes/Alabama/WindowsShare/DSS/724CardFinalHistory/HistorySlideshow.ts
  Type: MPEG transport stream
  
  Duration: 0:02:22
  Data Size: 290.41 MB
  Bit Rate: 17.07 Mbps
  
  Video Tracks:
  4096 MPEG-2, 1280 × 720, 16:9, 59.94 fps, 20.00 Mbps, progressive
  
  Audio Tracks:
  4098 MP2 stereo, 48 kHz, 384 kbps
  
  Stream Files:
  HistorySlideshow.ts (290.41 MB)
  
  
  We will test this tomorrow. I'll let you know.
  
• 0
  
  Devans April 22, 2010 02:20

  
  
  We loaded a 720p version onto a 30Mbps card and no dropouts have been reported yet.
  
• 0
  
  RokuLyndon April 22, 2010 02:50

  
  
  Throughput on the card is normally the culprit, epecially at the higher bitrates. You can test the card using the readperf command in the brightsing shell. Some cards don't perform as advertised. Also, if your vdieo has bitrate spikes, then that could explain it as welll. Some videos authored at 25 Mbps, can sometimes have spikes in the 35 - 40Mbps range.