Re: [FFmpeg-user] Fast encoding
On 14 Aug 2015, at 15:07, Robin Lery robinl...@gmail.com wrote: Hello sir, I am sorry I am very new at this. Would you please elaborate more, I didn't get you. For a program where 2 persons are talking an a studio, 80% of the screen stays the same, low bitrate is fine If it’s a sports-event like baseball, every changes constantly, high bitrate is needed. What’s needed depends. If you chose a low bitrate it’s too low for sport, if you choose High it’s too much, in the sense of wasted, for the ‘talking heads. Exactly this solves CRF/Constant quality. CRF can also be lowered or heightened by choosing another then the default value of 23. Lower numbers give higher quality, counter intuitive but that’s how it works. Try some examples and see what your outcome bitrates will become. Further the amount if bits you ’spend’ on audio depends, is it a good quality music peace or just 2 persons talking with each other. Trying wil help you understand how these things work. Happy learning. On 14 Aug 2015 18:28, Henk D. Schoneveld belca...@zonnet.nl wrote: On 14 Aug 2015, at 14:46, Robin Lery robinl...@gmail.com wrote: Hello, Thank you for your guidance. Actual the videos that I'll be encoding are for web video, so I think the bit rate matters. And as for the threads I want to use all the threads possible. I think -threads 0 balance the loads across all the cores automatically. What would be the best ffmpeg command in your opinion for fast encoding with constant specified bit rates (i.e 500k and 1000k)? ConstantBitrate is too much or too little CRF/ConstantQuality is …. Thank you. On Thu, Aug 13, 2015 at 7:43 PM, Moritz Barsnick barsn...@gmx.net wrote: On Thu, Aug 13, 2015 at 09:03:48 -0500, Steve Boyer wrote: On Wed, Aug 12, 2015 at 11:03 PM, Robin Lery robinl...@gmail.com wrote: I know about presets but faster presets lose the video quality. Are there It's my experience that CRF more directly affects the quality, and presets more influence filesize and encoding speed; a preset of slow will be ABOUT the same quality as veryfast but the bitrate between the two would be drastically different (in my opinion and eyes). The presets were designed to trade off speed versus size, using the same CRF and thereby (approximately) the same quality. But Robin is using: -maxrate 1000k thereby limiting what the encoder can achieve in terms of quality. I've used -threads=1 successfully after input, before output file name. Did Robin want to use more threads, or less? I understand ffmpeg automatically tries to choose the right amount of threads. (That said, my libx264 claims: Threading capabilities: no, but I read differing stuff on that.) Moritz ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Fast encoding
Hello sir, I am sorry I am very new at this. Would you please elaborate more, I didn't get you. On 14 Aug 2015 18:28, Henk D. Schoneveld belca...@zonnet.nl wrote: On 14 Aug 2015, at 14:46, Robin Lery robinl...@gmail.com wrote: Hello, Thank you for your guidance. Actual the videos that I'll be encoding are for web video, so I think the bit rate matters. And as for the threads I want to use all the threads possible. I think -threads 0 balance the loads across all the cores automatically. What would be the best ffmpeg command in your opinion for fast encoding with constant specified bit rates (i.e 500k and 1000k)? ConstantBitrate is too much or too little CRF/ConstantQuality is …. Thank you. On Thu, Aug 13, 2015 at 7:43 PM, Moritz Barsnick barsn...@gmx.net wrote: On Thu, Aug 13, 2015 at 09:03:48 -0500, Steve Boyer wrote: On Wed, Aug 12, 2015 at 11:03 PM, Robin Lery robinl...@gmail.com wrote: I know about presets but faster presets lose the video quality. Are there It's my experience that CRF more directly affects the quality, and presets more influence filesize and encoding speed; a preset of slow will be ABOUT the same quality as veryfast but the bitrate between the two would be drastically different (in my opinion and eyes). The presets were designed to trade off speed versus size, using the same CRF and thereby (approximately) the same quality. But Robin is using: -maxrate 1000k thereby limiting what the encoder can achieve in terms of quality. I've used -threads=1 successfully after input, before output file name. Did Robin want to use more threads, or less? I understand ffmpeg automatically tries to choose the right amount of threads. (That said, my libx264 claims: Threading capabilities: no, but I read differing stuff on that.) Moritz ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Fast encoding
On Thu, Aug 13, 2015 at 09:03:48 -0500, Steve Boyer wrote: On Wed, Aug 12, 2015 at 11:03 PM, Robin Lery robinl...@gmail.com wrote: I know about presets but faster presets lose the video quality. Are there It's my experience that CRF more directly affects the quality, and presets more influence filesize and encoding speed; a preset of slow will be ABOUT the same quality as veryfast but the bitrate between the two would be drastically different (in my opinion and eyes). The presets were designed to trade off speed versus size, using the same CRF and thereby (approximately) the same quality. But Robin is using: -maxrate 1000k thereby limiting what the encoder can achieve in terms of quality. I've used -threads=1 successfully after input, before output file name. Did Robin want to use more threads, or less? I understand ffmpeg automatically tries to choose the right amount of threads. (That said, my libx264 claims: Threading capabilities: no, but I read differing stuff on that.) Moritz ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Fast encoding
On Wed, Aug 12, 2015 at 11:03 PM, Robin Lery robinl...@gmail.com wrote: I know about presets but faster presets lose the video quality. Are there any hardware requirements I need to consider? Or are there any settings that I need to tweak? And lastly where do I place the -threads flag to encode video (before input or after input), I saw topics on thread but they were confusing. It's my experience that CRF more directly affects the quality, and presets more influence filesize and encoding speed; a preset of slow will be ABOUT the same quality as veryfast but the bitrate between the two would be drastically different (in my opinion and eyes). A comparison I found a while back is at http://mmmash.blogspot.com/2013/02/x264-settings-comparison-part-2-presets.html. There IS a noticable difference of the HD screen caps between the original and the ultrafast preset, but between original and veryfast, I don't see much of a difference. I've used -threads=1 successfully after input, before output file name. This is the command I am using now: ffmpeg -i input.mp4 \ -codec:v libx264 -tune zerolatency -profile:v main -preset medium -crf 23 -maxrate 1000k -bufsize 1k -s hd720 -codec:a libfdk_aac -pix_fmt yuv420p -movflags +faststart -threads 4 highoutput.mp4 \ -codec:v libx264 -tune zerolatency -profile:v main -preset medium -crf 23 -maxrate 500k -bufsize 5000k -s hd480 -codec:a libfdk_aac -pix_fmt yuv420p -movflags +faststart -threads 4 lowoutput.mp4 ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
