I just made a video in mov-formate containing 300pngs in 4k. Every single png ist roughly 6MB in filesize. The mov-file is just 8MB.

Seems weird to me. Is there maybe a quality loss in the video? The video looks fine but the size just seems so small.

  • $\begingroup$ You mean you used 300 PNGs to generate MOV file ... or you set in Output properties File Format > FFmpeg, Container > Quicktime, Video Codec > PNG? In the first case - QuickTime use H.264 codec by default, it is compressed format = smaller final size. $\endgroup$ – vklidu Jan 23 at 20:30

Video compression is designed for efficient throughput, favoring smaller files to minimize data rate.

video compression always implies a trade-off: it is easier to share and playback smaller files, but it comes at the cost of quality. Compression is always done by throwing away information, every time you encode video there will be some quality lost in favor of bandwidth.

Most video compression is lossy, whereas png can use lossless compression.

Will you perceive the difference? Probably not, as each image is visible for a very short period of time during video playback .

When the compression is too aggressive, that is when you will start to notice artifacts, like banding or macroblocking, to name a few. The fix those errors is to increase the data rate to the point where you are satisfied with the results.

It is possible to have visually lossless compression, and even lossless compression, resulting in huge files, but it is likely as well that your computer or hard drive cannot sustain the data-rate necessary to play them back smoothly.

The name of the game is Efficiency vs Quality: don't make the files any larger, or any more compressed, than what you can live with.

With that in mind, it makes even more sense to render always as an image sequence first, and encode as video later. Such workflow will allow you to experiment with different settings, and find the optimal size/data-rate/codec/container for your specific needs.

In closing, I would add that PNG is not a good format, Not only is it slower to compress, but it is plagued with a lot of problems, the most serious being it's handling of the alpha channel. If you are serious about creating video content, consider using OpenEXR as your intermediate format. Think of EXR as way to store an identical copy of the render layers you create in blender, without having to re-render.

For additional info read:

What image format encodes the fastest, or at least faster? PNG is too slow

  • $\begingroup$ Thank you so much for the detailed answer, that was a "on-point-introduction" into the topic and pretty much summed up all my questions. I will do my research. That png is not a good format suprises me, because every tutorial I have seen so far uses png for rendering, but I am still a noob $\endgroup$ – slammerton Jan 23 at 21:11
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    $\begingroup$ Not every video is a "tutorial". Think of them as entretainment, not as education. $\endgroup$ – susu Jan 23 at 21:17
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    $\begingroup$ One thing to know is that when you go from frame to frame in a video it may not be necessary for the entire frame to be updated with a new image. Perhaps there are only some small regions of the frame that have changed. $\endgroup$ – Allen Simpson Jan 23 at 22:50
  • $\begingroup$ @AllenSimpson yes, compression that relies on P frames and B frames does exactly that, to minimize changes. Those are used usually for delivery codecs, where there will be no more postproduction and the stream can be optimized further. For video that will be edited, composited or color corrected that type of compression should be avoided in favor of intraframe compression. $\endgroup$ – susu Jan 23 at 23:05
  • $\begingroup$ . For more info refer to Back to basics, gops explained and haivision.com/blog/all/… $\endgroup$ – susu Jan 23 at 23:05

Maybe, maybe not. Video files necessarily compress images to several factors smaller than they were. Check your render settings.


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