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Dropped Frames when recording to disc

I ran into an issue when recording to disc today. I set Wirecast to record to disc (MP4) with the setting 720p30 (4mbps). The goal for us it to record to disc then clean up any errors and then stream the clean version on YouTube that night.

After reviewing the footage, I noticed that frames were being dropped at several times throughout. We had 5 clips totaling about 1 hour of content and each clip had several dropped frames. The audio came in fine for each though.

I am using Wirecast 8.1 on a Windows (64 bit) machine. The machine has a i7 core processor, 16GB Ram. 

Would setting Wirecast to 720p30 (2mbps) resolve this? 

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  • Have you made sure the video display rate (preferences -> performance) matches your recording rate? A mismatch there will cause dropped frames.

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  • David Kazebeer Yes, I had it set for 30fps

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  • Nic Canobbio Make sure you have the best possible throughput. Avoid using the system disk.
    Separate internal SCSI drives are OK.
    Avoid using USB2 drives.
    If USB3 it should, ideally, be the only device on the bus. Even separate ports may be on the same bus. 
    Best is to use SSD or RAID0 striped drives. 7200 RPM disks may be OK though.
    Avoid spinning disks below 7200rpm
    Keep CPU below 80% and below 70% is even better.
    Make sure the drive never gets filled beyond 80% capacity. Especially for spinning disks, they can slow as they fill.
    Make sure you're not confusing variable frame rate with dropped frames. Wirecast records a variable frame rate to avoid dropped frames and keep motion smooth.
    If you're going to do post editing consider using MJPEG MOV instead of H.264.  

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  • CraigS Thank you for this. Would the external video capture card be causing this as well?

    I also noticed that a frame is sometimes dropped when put a graphic in live

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  • Nic Canobbio said:
    Would the external video capture card be causing this as well?

     It's conceivable. Make sure the driver is up to date. You may want to do a test recording using only the recording software that came with the card to take Wirecast out of the picture.

    Nic Canobbio said:
    I also noticed that a frame is sometimes dropped when put a graphic in live

     That's also possible. Wirecast Preview and Live Area use system resources as well and their display may not be completely accurate in some cases. I'd do a test recording and see if the dropped frame is recorded in.

    You should also monitor Wirecast Dropped Frames reporting in its top status report bar.

    It's not unusual to get a few dropped frames at the start of streaming and/or recording.

       

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