ffmpeg: recetas varias

Conversión definitiva sin pérdida apreciable y usando gpu
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```
ffmpeg.exe -i screenity3.webm -c:v h264_nvenc -c:a copy -preset slow -multipass fullres -vf scale=in_range=full:out_range=full -color_range 2 -rc-lookahead 0 -rc constqp  -bf 2 -spatial-aq 1 -aq-strength 8 -temporal-aq 1 -g 250 output.mkv
```

Normalize audio
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https://github.com/slhck/ffmpeg-normalize

https://github.com/slhck/ffmpeg-normalize

Recode using hardware acceleration
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ffmpeg -vsync 0 -hwaccel cuvid -c:v h264_cuvid -i input.mp4 -c:a copy -c:v h264_nvenc -b:v 5M output.mp4

(order of param is important, including -i position)

Recode videos in a folder
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#!/bin/bash

FILES=../*.flv
for f in $FILES
do
  echo "Processing $f."
  ffmpeg -i $f -strict -2 $f.mp4
done

MP4 a MP3
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 ffmpeg -i "bodypump 93 tracklist.mp4" -b:a 320K bodypump93.mp3

Listar dispositivos de audio
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 ffmpeg -list_devices true -f dshow -i dummy

Grabar el escritorio en hidpi:
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http://blog.cppse.nl/screen-capture-windows-10-hidpi-ffmpeg
ffmpeg -f dshow -i audio="Microphone (Realtek High Definition Audio)" ^
       -f gdigrab -framerate 30 -i desktop ^
       -c:v libx264 -preset ultrafast -crf 22 output.mkv


FFMPEG: avi 2 mp4

ffmpeg -i input.avi -c:v libx264 -crf 19 -preset slow -c:a aac -strict experimental -b:a 192k -ac 2 out.mp4

FFMPEG: Recortar vídeo

ffmpeg -i prod.avi -ss 00:00:00.0 -c copy -t 00:42:02 prod-first.avi

FFMPEG: Cambiar velocidad a vídeo sin perder calidad (20%)

ffmpeg -i input.mp4 -filter_complex "setpts=PTS/1.20;atempo=1.20" output20.mp4

FFMPEG: concatenar ficheros

Cam01.txt:
file '01-presentation.avi'
file '02-tools.avi'

ffmpeg -f concat -i Cam01.txt -c copy Cam01.mp4

FFMPEG: Mezclar vídeo con audio:

ffmpeg -i ..\..\01-presentation.avi -i es-01-presentation.mp3 -map 0:0 -map 1:0 -c:v copy -c:a copy es-01-presentation.avi

Resincronizar audio: ffmpeg -i produced.mp4 -itsoffset 0.3 -i produced.mp4  -vcodec copy -acodec copy -map 0:0 -map 1:1 synced.mp4