Take the 2-minute tour ×
Video Production Stack Exchange is a question and answer site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation. It's 100% free, no registration required.

I have a recorded video in HD format with the source file being about 2GB for 30 minutes of footage. I added it as a new Video Shot in WireCast intending to edit it, however, I got two problems. First, the quality drop tremendously regardless of what kind of output options I use and second, the output video is lagging and that is of course recorded in the final version.

I first tried to compress the video to reduce its size and I got it down to about 300MB but the results where exactly the same.

I then tried to stream the video from another computer on the same network using Desktop Presenter to reduce the load on the one where Wirecast was actually working, however, I got exactly the same results, if not worse.

Any tips on how I can deal with this issue?

share|improve this question
    
What HD format? What codec are you using? 2GB for 30 minutes of footage is very small, particularly for editing. 300MB for 30 minutes is pretty near uselessly small for any purpose even if you are at 720p. Any kind of re-encode at any of those file sizes is going to result in serious loss of quality. –  AJ Henderson Mar 17 at 20:11
    
The 2GB file is the raw format coming out from the Drift action camera that I'm using. Here's the properties of the file, not sure how I can retrieve more info: Type: MPEG Movie File Size: 2.5 GB Image Size: 1920 x 1080 Frame Rate: 29.97 Source Audio Format: 48000 Hz - compressed - Stereo Project Audio Format: 48000 Hz - 32 bit floating point - Stereo Total Duration: 00:29:32:16 Pixel Aspect Ratio: 1.0 –  mmvsbg Mar 17 at 20:18

1 Answer 1

up vote 0 down vote accepted

It sounds like your input is too compressed. Your current quality level is already below what Netflix uses for their full quality HD streaming and is right around Youtube's recommended settings for final output of video.

The problem is, this is already a very highly compressed level. Both compressing and decompressing an h.264 file take a lot of processing power. The more compressed the video, the more processing power it takes.

Since the file starts highly compressed, your CPU has to work hard to decode the video and then has to try to re-compress it for the stream. If it can't keep up with the frame rate, then you start getting quality drop and lag as it does it's best to keep up with the stream.

Further compressing the source video just amplified this problem, though if you have already pre-recorded the video, why not edit it offline and then export the video so that you can stream it without having to re-encode on the fly?

Wirecast isn't designed for editing, it is designed for streaming.

share|improve this answer
    
Thanks for the reply, the explanation helped me understand the situation a little bit better. I'm using Wirecast as I have a lot of pieces of information that I'm adding dynamically - something like a scoreboard for a basketball game while adding voice commentary at the same time. I'm doing this with a prerecorded file as a practice keeping in mind that in the future I'll have both situations - prerecorded offline files and live streaming where I'll have to achieve the same result in real time. I'm beginning to wonder whether Wirecast is the right software to use for this.... –  mmvsbg Mar 17 at 21:02
    
@mmvsbg - most likely you will need a switcher to handle the scoreboard stuff. It'll probably be difficult to do with just wirecast. If there aren't already questions about it, you can certainly ask more here. Things like video switchers and dedicated encoders will drastically simplify and improve your ability to do what you are trying to accomplish, though they aren't free. The cost has come down a lot, but still probably in the neighborhood of $1000 or more to do well. –  AJ Henderson Mar 18 at 2:55

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.