Video Recording Playback

I am looking for help in getting a recording to playback in the client
browser. I have the main Lynckia distribution running on my local LAN and
basic_example works, including the recording of my local video. Is there
any support for the playback of the recording file in the present code? I
can playback the file in VLC.

Hi all,
Peter is right, WebM does not support OPUS (or any of the other WebRTC audio codecs) as of now, only Vorbis. Current browser’s WebRTC implementations do not support Vorbis. That means we always need to transcode in order to have a HTML5-ready video tag.

Not even the mkv container supports VP8+OPUS, we took VP8+PCMU to be able to store the data in a container without transcodign and do that transcoding offline. Hopefully, in the near future WebM or a similar container will support OPUS+VP8, in the meantime the recommended thing to do is to use ffmpeg to get the file in the desired format.

Not transcoding in real-time saves a LOT of CPU.

Hopefully I managed to explain myself :slight_smile: please feel free to ask if you want any more details.

Cheers!–
Pedro Rodriguez

On 12 Dec 2013 at 14:33:27, Tom Chandler (tchandler48@gmail.com) wrote:

I add my vote for this also.

Thank You
Tom C

On Thu, Dec 12, 2013 at 2:58 AM, Jukka jukka.mahonen@gmail.com wrote:
I would like to know the answer to this question too! Playing records directly from browser without any transcoding would be nice feature.

  • Jukka

torstai, 12. joulukuuta 2013 10.07.16 UTC+2 Peter Hew kirjoitti:
It turns out that it is fairly easy to achieve playback in the client browser using the HTML5 video tag. The only problem is that the audio in the MKV container is PCM and the tag is expecting the WebM container, which is Vorbis encoded. I used ffmpeg to convert the file to WebM. This transcode is quite fast because the video is untouched. Since the recordings are non-realtime, the transcoding delay is not an issue, but I am curious as to why the audio is being converted to PCM for storage. Is it possible to just store the recording as a .webm file as generated by the client browser? Is there some advantage to using MKV format (more standard perhaps)?

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It turns out that it is fairly easy to achieve playback in the client
browser using the HTML5 video tag. The only problem is that the audio in
the MKV container is PCM and the tag is expecting the WebM container, which
is Vorbis encoded. I used ffmpeg to convert the file to WebM. This
transcode is quite fast because the video is untouched. Since the
recordings are non-realtime, the transcoding delay is not an issue, but I
am curious as to why the audio is being converted to PCM for storage. Is it
possible to just store the recording as a .webm file as generated by the
client browser? Is there some advantage to using MKV format (more standard
perhaps)?On Wednesday, December 11, 2013 10:07:18 AM UTC-8, Peter Hew wrote:

I am looking for help in getting a recording to playback in the client
browser. I have the main Lynckia distribution running on my local LAN and
basic_example works, including the recording of my local video. Is there
any support for the playback of the recording file in the present code? I
can playback the file in VLC.

We wanted to record the Licode video in different format but appears like
on MKV support coded in Licode. I was exploring the WebM
http://en.wikipedia.org/wiki/WebM and found that VP8 and VP9 + OPUS
supported in WebM. But MKV is more versatile than the WebM but not
supported in many HTML5 compliant browser to stream the video. Which
causing different pain for users to download and play them. I think
additional format support will add value to Licode.
Ref comparison of codecs
http://en.wikipedia.org/wiki/Comparison_of_container_formats.On Thursday, December 12, 2013 at 8:43:58 PM UTC+5:30, Pedro Rodriguez wrote:

Hi all,
Peter is right, WebM does not support OPUS (or any of the other WebRTC
audio codecs) as of now, only Vorbis. Current browser’s WebRTC
implementations do not support Vorbis. That means we always need to
transcode in order to have a HTML5-ready video tag.

Not even the mkv container supports VP8+OPUS, we took VP8+PCMU to be able
to store the data in a container without transcodign and do that
transcoding offline. Hopefully, in the near future WebM or a similar
container will support OPUS+VP8, in the meantime the recommended thing to
do is to use ffmpeg to get the file in the desired format.

Not transcoding in real-time saves a LOT of CPU.

Hopefully I managed to explain myself :slight_smile: please feel free to ask if you
want any more details.

Cheers!

Pedro Rodriguez

On 12 Dec 2013 at 14:33:27, Tom Chandler (tchan...@gmail.com <javascript:>) wrote:

I add my vote for this also.

Thank You
Tom C

On Thu, Dec 12, 2013 at 2:58 AM, Jukka <jukka....@gmail.com <javascript:>> wrote:

I would like to know the answer to this question too! Playing records
directly from browser without any transcoding would be nice feature.

  • Jukka

torstai, 12. joulukuuta 2013 10.07.16 UTC+2 Peter Hew kirjoitti:

It turns out that it is fairly easy to achieve playback in the client
browser using the HTML5 video tag. The only problem is that the audio in
the MKV container is PCM and the tag is expecting the WebM container, which
is Vorbis encoded. I used ffmpeg to convert the file to WebM. This
transcode is quite fast because the video is untouched. Since the
recordings are non-realtime, the transcoding delay is not an issue, but I
am curious as to why the audio is being converted to PCM for storage. Is it
possible to just store the recording as a .webm file as generated by the
client browser? Is there some advantage to using MKV format (more standard
perhaps)?


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I add my vote for this also.

Thank You
Tom COn Thu, Dec 12, 2013 at 2:58 AM, Jukka jukka.mahonen@gmail.com wrote:

I would like to know the answer to this question too! Playing records
directly from browser without any transcoding would be nice feature.

  • Jukka

torstai, 12. joulukuuta 2013 10.07.16 UTC+2 Peter Hew kirjoitti:

It turns out that it is fairly easy to achieve playback in the client
browser using the HTML5 video tag. The only problem is that the audio in
the MKV container is PCM and the tag is expecting the WebM container, which
is Vorbis encoded. I used ffmpeg to convert the file to WebM. This
transcode is quite fast because the video is untouched. Since the
recordings are non-realtime, the transcoding delay is not an issue, but I
am curious as to why the audio is being converted to PCM for storage. Is it
possible to just store the recording as a .webm file as generated by the
client browser? Is there some advantage to using MKV format (more standard
perhaps)?


You received this message because you are subscribed to the Google Groups
"lynckia" group.
To unsubscribe from this group and stop receiving emails from it, send an
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I would like to know the answer to this question too! Playing records
directly from browser without any transcoding would be nice feature.

  • Jukka

torstai, 12. joulukuuta 2013 10.07.16 UTC+2 Peter Hew kirjoitti:>

It turns out that it is fairly easy to achieve playback in the client
browser using the HTML5 video tag. The only problem is that the audio in
the MKV container is PCM and the tag is expecting the WebM container, which
is Vorbis encoded. I used ffmpeg to convert the file to WebM. This
transcode is quite fast because the video is untouched. Since the
recordings are non-realtime, the transcoding delay is not an issue, but I
am curious as to why the audio is being converted to PCM for storage. Is it
possible to just store the recording as a .webm file as generated by the
client browser? Is there some advantage to using MKV format (more standard
perhaps)?