Not an errant, gigantic file that is larger than the one you may have started with. It is this control of framerate and bitrate the keeps ffmpeg in check, and gives you predictable, repeatable results. (Except in transferring film to a tv screen, 24fps becomes 23.976fps, in most cases.) Of course 60fps is common for GoPro-like cameras, but here 30fps would be a reasonable choice. Framerate is either 24fps, 25fps, or 30fps for theatrical film, European tv, and North American tv, respectively. Maintaining the same framerate from source to slimmed-down file is essential, so that parameter is important. Often I work with large movie files from my bluray library, and create slimmed-down versions that are 1/3 to 1/2 the size of the original (20G original gives way to a file of 8-10GB with no perceptible loss of quality. For a noticeable improvement in video quality, the encoder bitrate should be set to at least 1.5 times those common practice bitrates: ie, 7,5p, 5,250 for 720p.
So limit threads on newer multithread desktops and laptops.Ĭommon practice for target bitrates (seen on Netflix, Amazon) vary with resolution, naturally: at least 5,000kbps for 1080p 3,500 for 720p. Several researchers have demonstrated that quality actually goes down if all cpu threads are engaged in encoding better to use fewer threads and even throttle ffmpeg with a 3rd party app (encoding does not slow down significantly, in my experience). May seem counter-intuitive, but a computer running on all threads, full throttle, to encode a video won't give you best results.
A constant bitrate is as effective as two-pass encoding for high-quality output, when paired with other key parameters, and is much quicker than two-pass. I get great results with VideoToolbox as encoder, using either GPU or software to accelerate, depending which machine I am using.Īs already mentioned, setting a constant bitrate, and adjusting it upward is key to producing a result that is nearly indistinguishable from a large source file. Jumping in for others who might stumble on the thread. I see the question's been answered and nearly two years ago.
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