[Ssc-dev] fine-tuning the ffmpeg build

Shawn Van Every vanevery at walking-productions.com
Wed Sep 28 20:10:30 EDT 2011


> Or why not just always do -acodec copy?

The low quality versions are outputting AMR-NB which doesn't really belong in MP4 either.

I would love to give faac/faad a shot and see how it goes.

On Sep 28, 2011, at 5:15 PM, Shawn Van Every wrote:

> Unfortunately MP4 containers with mp3 audio tracks aren't well supported by playback applications (such as QuickTime) and I don't think explicitly supported on android by the media player.  I would very much like us to output MP4 with AAC which is well supported.
> 
> Hans-Christoph Steiner <hans at at.or.at> wrote:
> 
>> 
>> Do we need to use AAC as the audio codec?  Its not well supported in  
>> ffmpeg internally, so it would require an external lib, faad or faac,  
>> I think.  How about mp3?  That should work fine in ffmpeg and in mp4  
>> files.  Or why not just always do -acodec copy?
>> 
>> .hc
>> 
>> On Sep 28, 2011, at 2:42 PM, Shawn Van Every wrote:
>> 
>>> It seems to work.  I haven't done anything more than very basic  
>>> tests though.
>>> 
>>> I did check it in to the SSCVideoProto repo.
>>> 
>>> Please let me know if you are able to get the audio encoding correct  
>>> with it.  I am using the same two commands that don't do anything  
>>> with the audio:
>>> 
>>>>> Super Duper High Quality (probably too high)
>>>>> (audio is already in AAC so it is simply copied but we should nail  
>>>>> down the settings there as well)
>>>>> ffmpeg -v 10 -y -i input.mp4 -vcodec libx264 -b 3000k -s 720x480 - 
>>>>> r 30 -acodec copy -f mp4 -vf 'redact=redact_unsort.txt' output.mp4
>>>>> 
>>>>> Lower Quality (Didn't get the audio right so using the -an to  
>>>>> strip it for now)
>>>>> ffmpeg -v 10 -y -i input.mp4 -vcodec libx264 -b 1000k -s  
>>>>> widthxheight -r 15 -vf redact=redact_unsort.txt -an -f mp4  
>>>>> output.mp4
>>> 
>>> 
>>> 
>>> 
>>> On Sep 28, 2011, at 2:36 PM, Hans-Christoph Steiner wrote:
>>> 
>>>> 
>>>> Hey Shawn,
>>>> 
>>>> I haven't heard back about the most recent ffmpeg update.  Is it  
>>>> working for you?  I think it would be possible to strip it down  
>>>> further.  Its including quite a bit now.  I think its at 5.7megs.
>>>> 
>>>> .hc
>>>> 
>>>> On Sep 14, 2011, at 11:04 PM, Shawn Van Every wrote:
>>>> 
>>>>> Hey Hans,
>>>>> 
>>>>> Fortunately the latest is 9 mb rather than 27 mb but it could  
>>>>> still use some optimizing and trimming.
>>>>> 
>>>>> For the input videos we want it to work with both our app and the  
>>>>> built in camera.  In our app we are using the camera defaults  
>>>>> anyway so the best thing to do is record a video using the built  
>>>>> in camera app at each of the quality settings as the source.
>>>>> 
>>>>> Unfortunately, this won't get us 100% of the way there as it is  
>>>>> possible that some devices will support different formats but for  
>>>>> now I think we should support what is spit out on the Nexus 1/ 
>>>>> Nexus S running 2.3 (I assume that is what you are running).
>>>>> 
>>>>> The output isn't completely nailed down but I think we want it to  
>>>>> be an MPEG-4 file with H.264 video and AAC audio.  size, bitrate,  
>>>>> framerate, sample rate, bit depth and so on should be consistent  
>>>>> with the input.  If it is a LOW quality original then use lower  
>>>>> quality settings, if it is HIGH then higher quality settings.
>>>>> 
>>>>> Here is what I have right now:
>>>>> 
>>>>> Super Duper High Quality (probably too high)
>>>>> (audio is already in AAC so it is simply copied but we should nail  
>>>>> down the settings there as well)
>>>>> ffmpeg -v 10 -y -i input.mp4 -vcodec libx264 -b 3000k -s 720x480 - 
>>>>> r 30 -acodec copy -f mp4 -vf 'redact=redact_unsort.txt' output.mp4
>>>>> 
>>>>> Lower Quality (Didn't get the audio right so using the -an to  
>>>>> strip it for now)
>>>>> ffmpeg -v 10 -y -i input.mp4 -vcodec libx264 -b 1000k -s  
>>>>> widthxheight -r 15 -vf redact=redact_unsort.txt -an -f mp4  
>>>>> output.mp4
>>>>> 
>>>>> -shawn
>>>>> 
>>>>> 
>>>>> On Sep 14, 2011, at 5:10 PM, Hans-Christoph Steiner wrote:
>>>>> 
>>>>>> 
>>>>>> Hey Shawn (and anyone else who's interested),
>>>>>> 
>>>>>> I want to fine-tune the ffmpeg build for SSC so its not 27 megs,  
>>>>>> uses
>>>>>> faster ARM assembly, etc..  If you could provide me with an example
>>>>>> video file to start from and the flags for the file you want to  
>>>>>> end up
>>>>>> with, I can nail down a small, optimized ffmpeg for it.
>>>>>> 
>>>>>> I can also work on the resulting format, if that's not already  
>>>>>> nailed
>>>>>> down.
>>>>>> 
>>>>>> .hc
>>>>>> 
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>>>>> 
>>>>> Shawn Van Every
>>>>> vanevery at walking-productions.com
>>>>> Mobile and Streaming Consulting
>>>>> http://www.walking-productions.com/notslop
>>>>> Author: Pro Android Media: http://amzn.to/eYb48C
>>>>> 
>>>> 
>>>> 
>>>> ----------------------------------------------------------------------------
>>>> 
>>>> “We must become the change we want to see. - Mahatma Gandhi
>>>> 
>>> 
>>> 
>> 
>> 
>> 
>> 
>> ----------------------------------------------------------------------------
>> 
>> I have always wished for my computer to be as easy to use as my  
>> telephone; my wish has come true because I can no longer figure out  
>> how to use my telephone."  --Bjarne Stroustrup (creator of C++)
>> 
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Shawn Van Every
vanevery at walking-productions.com
Mobile and Streaming Consulting
http://www.walking-productions.com/notslop
Author: Pro Android Media: http://amzn.to/eYb48C



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