Brightcove recommends that you use the following specifications for video files that you upload to your Media Library:
| Video Codec: | On2 VP6 |
| Encoding: | 2-Pass VBR |
| Resolution: |
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| Maintain Aspect Ratio: | Off (The above resolution settings will provide the correct aspect ratio.) |
| Frame Rate: | Same as source |
| Video Data Rate: | 464 kbps |
| Audio Data Rate: | 48 kbps |
| Total Data Rate: | 512 kbps |
| Keyframe: | At least every 6 seconds |
| Video Codec: | |
| Encoding: | 2 pass H.264 |
| Keyframe: | At least every 6 seconds |
For high resolution video renditions, you should upload H.264 source files to Brightcove. We've done some testing with H.264 files at different sizes and aspect ratios. Each of the following cases assumes H.264 2-pass encodes with 16-bit AAC audio at a sampling frequency of 44.1kHz and a bit rate of 192kbps. All bit rates do not include the audio bit rate, just the video. In the discussion, we compensate for the audio and give an approximate maximum length of the video for uploading to the server-side transcoding service. If video is interlaced, Brightcove will de-interlace it during transcoding. If your video will not be transcoded by Brightcove, you should de-interlace it before uploading it to Brightcove. Key frames should have a maximum distance of 6 seconds and do not need to be equidistant.
The approximate maximum lengths take into account the audio data rate and Brightcove's 2 GB maximum for uploaded files.
| Size | Aspect Ratio | Minimum Recommended Bit Rate | Approximate Maximum Length |
| 640x480 | 4:3 | Video with little motion, such as talking heads, can go as low as 900 kpbs with very good results. For overall high quality regardless of the level of motion, use at least 2672 kbps. This also refers to 720x480 sources as they are meant to be 640x480 but have a different pixel aspect ratio. | A video bit rate of 2672 kbps allows for a length of a little over an hour and a half. |
| 640x360 | 16:9 | Video bit rate can safely go as low as 2132kbps in almost all cases. | Nearly two hours. |
| 1024x768 | 4:3 | This format is used principally in screencasts or cropped HD sources. In the case of video, 4864kbps is sufficient. In the case of screencasts, we don't really need that much data, as very little changes from frame to frame. We can get away with the low end of what would do for 720p, which is 3136kbps. That's actually quite a bit more than we'd need, but we recommend a higher bitrate to allow for more frequent keyframing. Because we don't want strange ghosting of the mouse, it's best to have very frequent keyframes placed equidistant and twice a second (so every 15 frames in the case of a very smooth screen cast). If the frame rate of the screencast is not 30 (or 29.97), the data rate can be adjusted in parallel. So, if you have a screencast with a frame rate of 15, the data rate would be 1568kbps. This is generous bandwidth for a screencast, but it's necessary to eliminate ghosting and page tearing that often occurs when moving to something like H.264. | A little over 50 minutes of video |
| 1280x720 | 16:9 | The data rate for this format can go as low as 3136kbps for a talking head. When motion increases, even a little, the bit rate must increase quite a bit to compensate. In instances of low motion (meaning the subjects move, but the camera/frame does not), assuming lighting is adequate or ideal, 4512kbps is sufficient. For high motion, or to compensate for other factors, 5928kbps is sufficient (with a little bit of breathing room). | Between 40 and 45 minutes of video. |
| 1920x1080 | 16:9 stretched source | Many HDV and AVCHD cameras, even on the professional level, use 4:3 sensors and stretch the image from 1440x1080 to 1920x1080 in order to feign HD. When all is said and done, given the pulldown is always 4:2:0, this often results in an image that's almost equally as sharp at 960x540 with a pulldown of 4:2:2. With that in mind, there will be recommendations for this format at both 960x540 and 1920x1080. If you'd like to split the difference and upload in 720p, the previous 720p settings are applicable here. The 1920x1080 format will require a bit rate of 8024kbps to handle high motion. A talking head can safely go as low as about 6000kbps, but 8024kbps should cover most cases. That will allow for a little over a half an hour. Using the 960x540 format, you can use the same 3136kbps rate as a 720p talking head if you aren't upscaling to a larger size and if the motion isn't too heavy. | about an hour and 20 minutes with 3136kbps and a little over an hour with 3968kbps. |
H.264 is generally the best encoding standard for mobile applications. The iPhone supports H.264 (Baseline profile) at up to 2500kbps, 640x480, with 30 fps. However, an encoding rate of 512kbps should be more than adequate for mobile video.
When Brightcove transcodes your videos, we maintain the same aspect ratio as the source file. However, if you want a 16:9 aspect ratio, you need to make sure that your source video uses a true 16:9 aspect ratio, and not an anamorphic 16:9 aspect ratio. An anamorphic 16:9 format video is actually 4:3, and will be transcoded as 4:3.