example ffmpeg command line for mp4 & webm in same manifest

[Andy Hochhaus]

Hello,

Can anyone provide a pointer to an example ffmpeg command line which generates a dash manifest (*.mpd) containing both webm and mp4 content?

With such a manifest will shaka player automatically select the best content based upon the codecs available in the browser?

-Andy

[Joey Parrish]

Hi Andy,

To the best of my knowledge, ffmpeg can only output manifests for WebM DASH, not MP4.  To create the multicodec assets we published for Shaka, I only used ffmpeg to encode the files into various resolutions.  I used edash packager to package both the MP4 and WebM streams at the same time into one manifest.

For an example, here are the commands I used to create the first period of our short multi-period clip.  Does this help?

-Joey

COMMON_OPTS="-map 0:0 -an -threads 11 -cpu-used 4 -cmp chroma"

MP4_OPTS="-f mp4 -c:v libx264 -movflags +faststart -strict -2 -x264opts scenecut=0:open_gop=0:bframes=0:min-keyint=89:keyint=89 -flags +loop+cgop -profile:v baseline -level:v 3.0"

WEBM_OPTS="-f webm -c:v vp9 -keyint_min 89 -g 89 -dash 1"

# Encode MP4 in 4 resolutions:

ffmpeg -i sun.mp4 $COMMON_OPTS $MP4_OPTS \

  -b:v 1000k -vf scale=640:480 -y output/v-0480p-1000k-libx264.mp4

ffmpeg -i sun.mp4 $COMMON_OPTS $MP4_OPTS \

  -b:v 750k -vf scale=480:360 -y output/v-0360p-0750k-libx264.mp4

ffmpeg -i sun.mp4 $COMMON_OPTS $MP4_OPTS \

  -b:v 400k -vf scale=320:240 -y output/v-0240p-0400k-libx264.mp4

ffmpeg -i sun.mp4 $COMMON_OPTS $MP4_OPTS \

  -b:v 100k -vf scale=192:144 -y output/v-0144p-0100k-libx264.mp4

# Encode WebM in 4 resolutions:

ffmpeg -i sun.mp4 $COMMON_OPTS $WEBM_OPTS \

  -b:v 750k -vf scale=640:480 -y output/v-0480p-0750k-vp9.webm

ffmpeg -i sun.mp4 $COMMON_OPTS $WEBM_OPTS \

  -b:v 550k -vf scale=480:360 -y output/v-0360p-0550k-vp9.webm

ffmpeg -i sun.mp4 $COMMON_OPTS $WEBM_OPTS \

  -b:v 300k -vf scale=320:240 -y output/v-0240p-0300k-vp9.webm

ffmpeg -i sun.mp4 $COMMON_OPTS $WEBM_OPTS \

  -b:v 100k -vf scale=192:144 -y output/v-0144p-0100k-vp9.webm

# These outputs are only intermediate.  Rename them.

cd output

rename 's/webm/tmp.webm/' *.webm

rename 's/mp4/tmp.mp4/' *.mp4

# Package the content into one manifest.

packager --profile on-demand \

  input=v-0480p-1000k-libx264.tmp.mp4,stream=video,output=v-0480p-1000k-libx264.mp4 \

  input=v-0360p-0750k-libx264.tmp.mp4,stream=video,output=v-0360p-0750k-libx264.mp4 \

  input=v-0240p-0400k-libx264.tmp.mp4,stream=video,output=v-0240p-0400k-libx264.mp4 \

  input=v-0144p-0100k-libx264.tmp.mp4,stream=video,output=v-0144p-0100k-libx264.mp4 \

  input=v-0480p-0750k-vp9.tmp.webm,stream=video,output=v-0480p-0750k-vp9.webm \

  input=v-0360p-0550k-vp9.tmp.webm,stream=video,output=v-0360p-0550k-vp9.webm \

  input=v-0240p-0300k-vp9.tmp.webm,stream=video,output=v-0240p-0300k-vp9.webm \

  input=v-0144p-0100k-vp9.tmp.webm,stream=video,output=v-0144p-0100k-vp9.webm \

  --mpd_output dash.mpd

# Remove the intermediate files.

rm *.tmp.webm *.tmp.mp4

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[Joey Parrish]

Oh, and I forgot to answer the second part of your question.  Yes, Shaka will filter out any streams in a manifest that the browser can't parse/decode.

If your browser supports WebM but not MP4, Shaka will play WebM from a multicodec manifest.  If your browser supports MP4 but not WebM, Shaka chooses MP4.

If your browser supports both, the choice is arbitrary and based on what appears first in the manifest.

Thanks,

Joey