I have not tested many other videos and I also have quite a lot to learn about SR like if I feed it different training material will I get a better result. Bear in mind that my test was upscaling from 640x360 flv file to 1920x1080 mp4. I felt on my test videos that lanczos did an ever so slightly better job. Before proceeding it is worth saying that I was not overly impressed by the result.
# ffmpeg-normalize *.I realise this question is pretty old now but it still comes up quite high in search results so I would like to document how I got the "sr" to work (August 2020) in case it can help someone else.
ffmpeg-normalize supports batch processing, copying of the video and subtitle streams, retaining the original audio and has all the options for exact control :). There is a tool that automates all of this. Combining it with the loudnorm filter, the full command line would be: If your FFmpeg has soxr support you can enable it with the aresample filter -filter:a aresample=resampler=soxr:out_sample_rate=48000:precision=28. While the FFmpeg sample rate conversion is generally very good, there is a better sample rate converter called SoX Resampler. We also want to target the overall loudness to be -23 LUFS (Loudness Units, referenced to Full Scale). So in order to resample it back down to the same as the source we use -ar 48000 for 48KHz or -ar 44100 for 44.1KHz. The loudnorm filter resamples the audio to 192KHz. Pass 1: # ffmpeg -i audio.dts -filter:a loudnorm=print_format=json -f null NULL Use 2 for stereo, 6 for 5.1 and 8 for 7.1 sources. 20 is default and is suitable for 16bit output, with noise shaping/dithering filters. 28-33 is considered very high quality and suitable for 24bit audio. Slects the swr or soxr sample rate conversion engine.
Range is -99.0 - +0.0.Įnables json output which is needed to get the parameters for the second pass. Gain is applied before the true-peak limiter. For EBU R128 normalization a target of -23dB should be used. Normalize by linearly scaling the source audio.
Then you use those properties as input in the second pass. The first pass checks the audio properties of the source file. The loudnorm filter works best when you run it in two passes. Here we'll go through audio normalization using the loudnorm filter. Ffmpeg is a great tool for audio/video encoding.
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