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Compressing 3 hours of footage for youtube

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Ben Hilton
Compressing 3 hours of footage for youtube
on Oct 24, 2013 at 12:49:23 pm

Hey everyone,
I am planning on shooting some live classes this year, edit them and uploading them to youtube daily. I will be shooting about 3-4 hours of 1080P 29.97 AVCHD XDcam footage everyday. My problem is that my internet is really not good enough to upload 5 GB of footage a day, which is about how small I can compress it to in 720P. If possible I am wanting to be able to compress the footage to under 1GB. I am will to go down to SD if need be. Any compression thoughts on this? Maybe live-stream? If so, any thoughts on that, as far as cheap effective programs?
Thanks for any help,
Ben


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Ivan Myles
Re: Compressing 3 hours of footage for youtube
on Oct 24, 2013 at 3:53:03 pm

The target bitrate is calculated as follows:

1GB/4hr = (1024^2 kB/GB)*(8 bits/byte)/(14,400 sec) = 583 kbps

Minimum acceptable picture quality can be maintained at about 0.07 bits per pixel when encoding with H.264. We can calculate bpp at different frames sizes and frame rates as follows:

(583x1024) / (1920x1080x30) = 0.01 bpp @ 1080p30
(583x1024) / (1280x720x30) = 0.02 bpp @ 720p30
(583x1024) / (854x480x30) = 0.05 bpp @ 480p30
(583x1024) / (854x480x24) = 0.06 bpp @ 480p24
(583x1024) / (854x480x20) = 0.07 bpp @ 480p20

Therefore, in order to meet a target file size of 1GB and maintain acceptable picture quality a 4hr video should be encoded at 854x480 resolution with a frame rate of 20-24fps. If the video must be recorded at 29.97fps, try to keep the length closer to 3hr or relax the 1GB constraint.


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Ben Hilton
Re: Compressing 3 hours of footage for youtube
on Oct 25, 2013 at 11:57:06 am

Thank you so much for your help. If I encoded the 4 hour videos to 854x480@24FPS, what Bit-Rate would I use to still match the 1 GB limit. Also, do you have any ideas as to a more efficient codec than H.264?
Thanks,
Ben


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Ivan Myles
Re: Compressing 3 hours of footage for youtube
on Oct 25, 2013 at 5:16:59 pm

[Ben Hilton] "If I encoded the 4 hour videos to 854x480@24FPS, what Bit-Rate would I use to still match the 1 GB limit."

Total bitrate will be 583 kbps. It is defined by the target file size (1GB) and the length of the video (4hr).

Subtract the audio bitrate from 583 kbps to determine the target video bitrate. I think 64 kbps mono audio should work well for a lecture, which leaves about 520 kbps for video.

Unless the footage can be edited to about 3 hours, you might consider cropping the frame to 640x480, scaling the resolution to 640x360, or reducing the frame rate to 15fps. Otherwise the encoded video will likely have macroblocking, which will make it very difficult to see detail on presentation slides or a white board. Try encoding a short test file at a few different settings to determine the best alternative.

[Ben Hilton] "Also, do you have any ideas as to a more efficient codec than H.264?"

H.264, and specifically the x.264 implementation, is the most efficient codec available at this time. H.265 is still in development.


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Ben Hilton
Re: Compressing 3 hours of footage for youtube
on Oct 29, 2013 at 8:31:13 am

Thank you so much for your help, If I can get it down to three hours, what would you suggest from there?


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Ivan Myles
Re: Compressing 3 hours of footage for youtube
on Oct 29, 2013 at 4:26:06 pm

Try encoding a test clip that is a few minutes in length with the following parameters and upload to YouTube (set Format and Level first):

Format: H.264
Level: 3.1
Profile: High
TV Standard: Either will work; use same setting as the source material
Width: 854
Height: 480
Frame Rate: 24 fps [1]
Aspect: Square Pixels (1.0)
Bitrate Encoding: VBR, 2-pass
Target Bitrate: 0.52 [2]
Maximum Bitrate: 0.78 to 1.0 [3]

Scroll down to the Advanced section and set Key Frame Distance to 72 frames.

On the bottom of the panel enable Use Maximum Render Quality.

Open the Multiplexer tab and check that Multiplexer is set to MP4 and Stream Compatibility is Standard.

Open the Audio tab and set the following:

Codec: AAC
Output Channels: Mono
Frequency: Same as source (typically 44.1 or 48 khz)
Audio Quality: High
Bitrate: 64 kbps
Precedence: Bitrate

When ready to encode, click the Export button; do not use Queue when scaling the video.

After encoding the test file(s), check for any quality issues. If all looks good, upload to YouTube and verify that the final YouTube version looks OK. If so, go back and encode the entire lecture using the best test settings. If not, try reducing the frame dimensions or frame rate and encode/upload again.

Notes:

[1] You will get best results by exporting with the same frame rate as the source material. As per our previous discussion, 24 fps allows you to hit the file size target. If the source footage is 30 fps, consider exporting at 15 fps (every other frame skipped) or 20 fps (every third frame skipped) instead.

[2] The 0.52 Mbps bitrate setting should allow you to meet the 1GB file size constraint. The uploaded file will be re-encoded by YouTube to about the same bitrate, which might impact image quality. If the test file has quality issues, try 640x360 instead.

[3] YouTube will re-encode the file using a maximum bitrate around 1.5x the average bitrate. Try two or three different settings to see if there is any impact on picture quality as it appears on YouTube. I suggest 0.78 and 1.0 Mbps.

Other: If you are exporting the file from Premiere Pro (as opposed to Adobe Media Encoder) and your computer has an Nvidia graphics card, go into the Project > General settings and enable GPU acceleration (Renderer: Mercury Playback Engine GPU Acceleration). It should reduce the time required to encode the files.


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Valerie Ng
Re: Compressing 3 hours of footage for youtube
on Nov 12, 2013 at 6:48:23 pm

Hi Ivan,

I have worked with After effects before and am new to burning for dvd. I have for the past three weeks been struggling with this movie. I have tried compressing with Encoder and After Effects, then burning on a dvd. Though I am having two main issues. One I have the black bars on either side of my screen even though it is set up for widescreen. The other issue is that the text looks bad when I burn it onto a dvd. The DVD I am trying to burn effectively and asap is for a 50 inch HDTV and widescreen. What I have gathered is that the TV is a 1080p and that the pixel ratio is 16:9. I have tried compressing several ways with different bitrates and have not found the proper settings. If you can assist me that would be AMAZING! :)
thanks
-Val Ng


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