[FFmpeg-devel] [PATCH] write AC-3 metadata

Justin Ruggles justin.ruggles
Wed Dec 22 19:26:13 CET 2010

On 12/21/2010 08:25 PM, Justin Ruggles wrote:

> On 12/21/2010 06:13 PM, Justin Ruggles wrote:
>> On 12/21/2010 05:20 PM, Kieran Kunhya wrote:
>>>> Date: Tuesday, 21 December, 2010, 21:56
>>>> Hi,
>>>> This patch adds writing of AC-3 metadata to the AC-3
>>>> encoder.
>>>> I chose to use AVOption instead of trying to move the
>>>> metadata API to
>>>> libavcodec because the AC-3 metadata isn't just regular
>>>> metadata.  Even
>>>> though it is not audio data, many of the fields actually
>>>> affect decoding.
>>>> Some of the options use integers to set a specific code
>>>> value rather
>>>> than using a float value directly (e.g. mixing
>>>> levels).  It looks a bit
>>>> ugly, but I chose to do this because there are only a few
>>>> valid values.
>>>>  Trying to determine which value the user wants by
>>>> comparing floats
>>>> seems more complicated.  Plus this allows the help
>>>> text to tell the user
>>>> what the valid values are for those options.
>>>> Thanks,
>>>> Justin
>>> Is there any possibility of making these metadata options changeable per frame? Quite useful for broadcast applications when the metadata needs to be different during advertising or during specific programming.
>> If you're changing programs, you should probably re-initialize encoding
>> anyway.  Other things can change too like bitrate, number of channels,
>> etc...
>> As for setting metadata per-frame, it is possible.  New patch attached.
>>  It adds an option to enable per-frame validation of metadata so that it
>> won't significantly affect performance when the option is not enabled.
> oops. disregard this patch. i forgot the most important part. i'll send
> a new one in a little while.

New patch attached.

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