guix.gnu.org/videos don't play on iOS

Guix,

A sympathetic PotentialUser reported that they were unable to play

any of our home-page videos on their iPad. Even Firefox didn't

work.

Leo pointed out that we use the VP9 and Opus codecs — both of

which are still not supported by Apple[0][1]. Nor is Vorbis.

nginx can easily sniff iOS/Macintosh user agents and serve them an

inferior format to match, such as h264 with MP3 audio, which can

both be encoded using free software in Guix.

Kind regards,

T G-R

[0]: https://caniuse.com/#feat=opus

[1]: https://caniuse.com/#search=vp9

On Thu, Jul 30, 2020 at 01:08:48AM +0200, Tobias Geerinckx-Rice via Bug reports for GNU Guix wrote:

Here is where the videos are created:

------

$(NUMBER).clino.$(VIDEO).webm: \

$(VIDEO)/$(LOCALE_LANG)/durations.txt \

$(VIDEO)/$(LOCALE_LANG)/audios/all.mp3

ffmpeg -y -f concat -vsync cfr \

-i $(VIDEO)/$(LOCALE_LANG)/durations.txt \

-i $(VIDEO)/$(LOCALE_LANG)/audios/all.mp3 \

-c:a libopus -b:a 192k \

-c:v libvpx-vp9 -crf 31 -b:v 0 -pix_fmt yuv420p \

-af apad -shortest \

-vf fps=25 -threads 4 $(VIDEO)/$(LOCALE_LANG)/videos/$@;

make clean_noCli

------

So, we'd need to add a target that did "-c:a copy -c:v libx264" and add

some logic to create two videos instead of one. I didn't look into it

closely yet to see if that will be simple or not.

On Wed, Jul 29, 2020 at 07:26:57PM -0400, Leo Famulari wrote:

Coming back to this, I don't remember why I suggested "c:a copy". We

would want to transcode the audio as well, because the standard codec is

h264/aac.