AW: MP4 files wit AAC

Thu Sep 15 10:33:19 UTC 2016

Hi Keith.

What if you leave out the video part? Can you then play the file ?

Apparently avenc_aac produces 'ER Parametric' AAC audio and your other
encoder (as well does faac) produces 'LC - Low Complexity' AAC. See
https://en.wikipedia.org/wiki/MPEG-4_Part_3 on various AAC format (look for
Audio Object Type).

Perhaps WMP does not like 'ER Parametric' AAC as object type?

Using GStreamer for many years, faac has always just worked while all
problems I have encountered (others may have a different experience) with
AAC audio has always been tracked back to trying to use avenc_aac, Maybe
faac is not as advanced as avenc_aac and maybe there are license issues,
but it does what it does well and has made my life easier. Leaving out faac
in some distribution has caused many pains over the years and a lot of
mails here on the mailing list.

For the GStreamer team:

The 'avenc_aac' seems to ignore when using the following caps filter

avenc_aac ! 'audio/mpeg,base-profile=(string)lc' ! ....

It still produce 'ER Parametric' AAC. Shouldn't avenc_aac produce LC AAC or
at least protest?

Btw. the program 'mediainfo' can also reveals the settings of a media file.

Best regards

On Thu, Sep 15, 2016 at 11:44 AM, Thornton, Keith <keith.thornton at zeiss.com>
wrote:

> Hi,
>
> ffplay outputs the following form y file with avenc_aac
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/temp/mit_audio__0000.mp4':
>   Metadata:
>     major_brand     : mp42
>     minor_version   : 0
>     compatible_brands: mp42mp41isomiso2
>     creation_time   : 2016-04-28 10:55:59
>   Duration: 00:00:19.74, start: 0.000000, bitrate: 12263 kb/s
>     Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
> 1920x1080 [SAR 1:1 DAR 16:9], 12133 kb/s, 50 fps, 50 tbr, 5k tbn, 100 tbc
> (default)
>     Metadata:
>       creation_time   : 2016-04-28 10:55:59
>       handler_name    : VideoHandler
>     Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo,
> fltp, 168 kb/s (default)
>     Metadata:
>       creation_time   : 2016-04-28 10:55:59
>       handler_name    : SoundHandler
>    2.99 A-V: -0.020 fd=  23 aq=   15KB vq= 1069KB sq=    0B f=0/0
>
> And
>
>
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/temp/mit_audio__0000_ffmpeg.
> mp4':
>   Metadata:
>     major_brand     : isom
>     minor_version   : 512
>     compatible_brands: isomiso2avc1mp41
>     encoder         : Lavf57.19.100
>   Duration: 00:00:19.66, start: 0.036281, bitrate: 12271 kb/s
>     Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
> 1920x1080 [SAR 1:1 DAR 16:9], 12133 kb/s, 50 fps, 50 tbr, 10k tbn, 100 tbc
> (default)
>     Metadata:
>       handler_name    : VideoHandler
>     Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz,
> stereo, fltp, 128 kb/s (default)
>     Metadata:
>       handler_name    : SoundHandler
>    2.25 A-V:  0.004 fd=  15 aq=   12KB vq= 1096KB sq=    0B f=0/0
>
> For the file after audio has been transcoded.
> Video was not transcoded  (-vcodec=copy)
>
> According to ffplay
>
> Ok for WindowsMediaplayer or QuickTimePlayer:
>
>     major_brand     : isom
>     minor_version   : 512
>     compatible_brands: isomiso2avc1mp41
>
> Not Ok for WindowsMediaplayer or QuickTimePlayer:
>
>     major_brand     : mp42
>     minor_version   : 0
>     compatible_brands: mp42mp41isomiso2
>
>
> -----Ursprüngliche Nachricht-----
> Von: gstreamer-devel [mailto:gstreamer-devel-bounces at lists.freedesktop.org]
> Im Auftrag von Tim Müller
> Gesendet: Donnerstag, 15. September 2016 09:56
> An: gstreamer-devel at lists.freedesktop.org
> Betreff: Re: AW: MP4 files wit AAC
>
> On Thu, 2016-09-15 at 05:29 +0000, Thornton, Keith wrote:
>
> Hi Keith,
>
> > If I use ffmpeg to transcode them from mp4/h264/aac to mp4/h264/aac
> > the files are then playable so what I need to know is what is ffmpeg
> > doing that the avenc_aac is not doing.
>
> It would be interesting to see the output of gst-discoverer-1.0 -v and
> ffplay on a gst/avenc_acc-produced file vs. an ffmpeg-transcoded one then.
>
> Maybe it's a codec profile thing or so.
>
> Cheers
>  -Tim
>
> --
> Tim Müller, Centricular Ltd - http://www.centricular.com
>
> Join us at the GStreamer Conference!
> 10-11 October 2016 in Berlin,
> Germany
> https://gstreamer.freedesktop.org/conference/
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