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Does anyone know if the video size affects the quality of a video? For example, if you make a video 320x240 does it make it a different quality to 640x480 or are you not altering the quality at all and literally just changing the size?

it depends what size you play it in

but generally the smaller the video size, the better the quality.

But if you play it in the normal size of video sharing sites, not full screen, just the usual video player size, which I believe is 640x480, does it matter if you make the video 320x240 since it will get played at 640x480 anyway?

Which size would lead to the best quality on playing at 640x480?

if it's gonna get played at 640 x 480 then i recon it's best to record at that size. i'm no expert in this field though and i'm sure another member will be able to offer more help.

No it doesn't affect the quality. The main two basic elements that affect video picture quality are bitrate and framerate. Framerate tends not to vary too much and is usually 25fps or 29.97fps. Bitrate varies dramatically.

A video that has been created at a higher bitrate can be created as a larger physical size, hence larger videos are generally of better quality.

EDIT: Many video exporter applications will automatically create a video at a higher bitrate if a larger physical size is set, in order to ensure the video is of sufficient quality (unless the user manually sets the bit rate).

Skate got to disagree on this one. As you've hinted at in your edit bitrate is effected by the resolution. Keep everything else the same and increase the resolution and the bitrate will increase as well as more data is stored

If the 640*480 was going to be viewed at 320*240 then might as well use 320*240 but if 320*240 is going to be up scaled to 640*480 then not so. Unless other compromises have to be made to achieve it the 640*480 clip is always going to be the better, all be it larger, clip.

To make it simpler to understand at a basic level think of a video clip as a sequence of photos. The bigger the photo, the bigger the file, but the finer the detail that can be resolved. (Yes I know it isn't that simple and video isn't encoded as individual frames before anyone points it out but it makes it easier to grasp the principal)
Now think of bitrate as the individual file size of the photo. If you keep the same file size but a larger photo you need to compress it more and depending on the image and the compression used depends on how well it retains that detail. Sometimes the small file will look better up scaled, sometimes not

In the real world quite often it's quicker to just try out both and see which is the best compromise

southlondonphil Wrote:Does anyone know if the video size affects the quality of a video? For example, if you make a video 320x240 does it make it a different quality to 640x480 or are you not altering the quality at all and literally just changing the size?

I'm experimenting.
Same clip, video bitrate, audio, everything.
Only the resolution is changed.
Look at the file size.
Original 1024x768


Down 512x288


Up to 1280x720


Original 1024x768 caps:


Down 512x288 caps:


Up to 1280x720 caps:


Conclusion - the original resolution gives the best quality ... I think.


PS sorry, the page over to the forum

Your example doesn't really prove a point as you are just rescaling the original source rather than the original source being changed. Add to the fact you are also adjusting the aspect ratio causing distortion and hence loss of quality and it renders the actual results, although not the argument, invalid

Red Wrote:Your example doesn't really prove a point as you are just rescaling the original source rather than the original source being changed. Add to the fact you are also adjusting the aspect ratio causing distortion and hence loss of quality and it renders the actual results, although not the argument, invalid

If the bitrate is higher than the original.
Where did you get more image data?
There is no real content behind it.
Only videoeditor program generates, not "true" data.

Only repeat: Conclusion - the original resolution gives the best quality.
-for the original question

Sorry the bad english

Peace