Convert old mov files to more modern mp4 x264 or AV1

Make you old videos watchable

Posted on 3 mins read
AV1 FTW!. src: https://commons.wikimedia.org/wiki/File:AV1_logo_2018.svg

AV1 FTW!. src: https://commons.wikimedia.org/wiki/File:AV1_logo_2018.svg

Some time ago I’ve discovered a bunch of old QuickTime files on my NAS. None of those clips could be played back via NextCloud’s browser player as they were encoded with old school mjpeg video codec & low quality mono pcm_s16be audio.

This is what mediainfo told me about those files:

Video
Format                 : JPEG
Codec ID               : jpeg
Bit rate mode          : Variable
Bit rate               : 3 827 kb/s
Width                  : 640 pixels
Height                 : 480 pixels
Display aspect ratio   : 4:3
Frame rate mode        : Constant
Frame rate             : 30.000 FPS
Color space            : YUV
Chroma subsampling     : 4:2:2
Bit depth              : 8 bits
Compression mode       : Lossy
Bits/(Pixel*Frame)     : 0.415
...
Audio
Bit rate mode          : Constant
Bit rate               : 128 kb/s
Channel(s)             : 1 channel
Sampling rate          : 7 840 Hz
Bit depth              : 16 bits

I’ve decided to transcode them to hopefully a future-proof format. After a bit of testing I’ve decided to stick with x264 and Opus @ cfr 18 as it:

  • provided v.good visual quality
  • transcocding is pretty fast
  • is recognised by most of the video players (including browsers)
  • can be streamed nicely

I also decided to upsample the audio, so it can be easily mixed & edited during video editing.

Converting those file to AV1 deemed to be pointless as the file size savings are not worth the transcoding times. On average it took more than 45 minutes to transcode a 45s mov file described earlier!!!

File size comparison

  • Original file: 22,890,348 bytes
-c:v profile -c:a File size video audio
libx264 -crf 10 aac 24,368,779B 23042kB 730kB
libx264 -crf 10 mp3 24,727,469B 23042kB 1067kB
libx264 -crf 10 opus 24,511,013B 23042kB 868kB
libx264 -crf 18 aac 10,118,378B 9126kB 730kB
libx264 -crf 18 mp3 10,477,856B 9126kB 1067kB
libx264 -crf 18 opus 10,260,612B 9126kB 868kB
libaom-av1 constant opus 1,439,833B kB 868kB
libaom-av1 constrained opus 8,113,605B 7217kB 697kB
libaom-av1 2-pass opus 13,537,391B 12329kB 868kB

x264 crf 10 & mp3 

ffmpeg \
    -i input.mov \
    -vcodec libx264 \
    -preset slow \
    -tune film \
    -crf 10 \
    -c:a libmp3lame \
    -ar 48000 \
    -ac 2 \
    -b:a 192k \
    output_mp3.mp4

x264 crf 10 & aac 

ffmpeg \
    -i input.mov \
    -vcodec libx264 \
    -preset slow \
    -tune film \
    -crf 10 \
    -c:a aac \
    -ar 48000 \
    -ac 2 \
    -b:a 192k \
    output_aac.mkv

x264 crf 10 & Opus 

ffmpeg \
    -i input.mov \
    -vcodec libx264 \
    -preset slow \
    -tune film \
    -crf 10 \
    -c:a libopus \
    -ac 2 \
    -ar 48000 \
    -b:a 192000 \
    output_opus.mkv

AV1 & Opus

Unfortunately I wasn’t able to convert mov files directly to AV1, so I used the output_opus.mkv from previous example.

Constant quality 

ffmpeg \
    -i output_opus.mkv \
    -c:v libaom-av1 \
    -crf 30 \
    -b:v 0 \
    -strict experimental \
    -c:a copy \
    av1_constant.mkv

Constrained quality 

ffmpeg \
    -i output_opus.mkv \
    -c:v libaom-av1 \
    -minrate 500k \
    -b:v 2000k \
    -maxrate 2500k \
    -strict experimental \
    -c:a copy \
    av1_constrained.mkv

2-Pass 

ffmpeg \
    -y \
    -i output_opus.mkv \
    -c:v libaom-av1 \
    -strict -2 \
    -b:v 2000K \
    -maxrate 2500K \
    -pass 1 \
    -f matroska NUL \
    && \ 
fmpeg \
    -i output_opus.mkv \
    -c:v libaom-av1 \
    -strict -2 \
    -b:v 2000K \
    -maxrate 2500K \
    -pass 2 \
    -c:a copy \
    av1_2pass.mkv

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