ffmpeg/avconv: transcode using same codec and params as input

Question

Is there a way to tell ffmpeg and/or avconv to use for the output the same codec as the one the input is encoded with, but do the transcoding?

I\'m looking for somet

Answer 1

ffmpeg doesn't have a feature to copy the same bitrate, but it will automatically copy the frame rate, width, height, pixel format, aspect ratio, audio channel count, audio sample rate, etc, (encoder dependent).

I don't recommend copying the same bitrate for a variety of reasons that would end up as several paragraphs. In short, let the encoder deal with that automatically.

However, here is a simple bash script. You'll need to adapt it to include audio stream info and whatever other parameters you want.

#!/bin/bash
# Copies the same video codec and bitrate: usually this is not a good idea.
# Usage: ./vidsame input output

echo "Calculating video bitrate. This can take a while for long videos."

# Alternatively you could just use ffprobe to get video stream bitrate,
# but not all inputs will show stream bitrate info, so ffmpeg is used instead.

size="$(ffmpeg -i "$1" -f null -c copy -map 0:v:0 - |& awk -F'[:|kB]' '/video:/ {print $2}')"
codec="$(ffprobe -loglevel error -select_streams v:0 -show_entries stream=codec_name -of default=nk=1:nw=1 "$1")"
duration="$(ffprobe -loglevel error -select_streams v:0 -show_entries format=duration -of default=nk=1:nw=1 "$1")"
bitrate="$(bc -l <<< "$size"/"$duration"*8.192)"

ffmpeg -i "$1" -c:v "$codec" -b:v "$bitrate"k "$2"

echo
echo "Duration: $duration seconds"
echo "Video stream size: $size KiB"
echo "Video bitrate: $bitrate kb/s"
echo "Video codec: $codec"

If you want additional parameters use ffprobe to view a list of what's available:

ffprobe -loglevel error -show_streams input.mkv

Then use -select_entries as shown in the script.

Note that codec_name won't always match up with an encoder name, but usually it will Just Work. See ffmpeg -encoders.