[FFmpeg-soc] [soc] libavsequencer [PATCH 01/08] Music module public API header file.

[Ronald S. Bultje]

Hi,

On Tue, Jul 13, 2010 at 5:55 PM, Sebastian Vater
<cdgs.basty at googlemail.com> wrote:
> Vitor Sessak a écrit :
>> On 07/13/2010 10:11 PM, Sebastian Vater wrote:
>>> Vitor Sessak a écrit :
>>>> On 07/07/2010 10:46 PM, Sebastian Vater wrote:
>>
>> [...]
>>
>>>>> /**
>>>>>   * Opens and registers module to the AVSequencer.
>>>>>   *
>>>>>   * @param avctx the AVSequencerContext to store the opened module
>>>>> into
>>>>>   * @param module the AVSequencerModule which has been opened to be
>>>>> registered
>>>>>   * @return>= 0 on success, a negative error code otherwise
>>>>>   *
>>>>>   * @note This is part of the new sequencer API which is still under
>>>>> construction.
>>>>>   *       Thus do not use this yet. It may change at any time, do not
>>>>> expect
>>>>>   *       ABI compatibility yet!
>>>>>   */
>>>>> int avseq_module_open(AVSequencerContext *avctx, AVSequencerModule
>>>>> *module);
>>>>
>>>> Hmm, I think I don't really understand what this function do. Suppose
>>>> you want to write a very short test program to play a MOD file using
>>>> the libraries. Roughly, what functions it will call, in which order
>>>> and with which parameters?
>>>
>>> To be honest, I added this prototype only for now to see if the way I
>>> want to add them is compatible with FFmpeg style guide. Wanted just to
>>> avoid adding functions and all follow a wrong guideline. But the suppose
>>> is to load a module from disc and register it to the module list in
>>> avctx).
>>
>> Guideline-wise it is fine, but I don't think functions should be added
>> to the BSS structs without a very good reason.
>
> That's clear! Just want to mention the point, that the user today
> expects the feature of having multiple (in this case modules) files
> opened at once and thus editing them. We're not anymore in the eighties
> were it was common just to have one file opened at the same time.
>
> So I thought of a way of allowing the user exactly that, that's why I
> plan to add multiple modules to AVSequencerContext. The programmer
> developing the GUI has to take care of this list though mostly by itself.
>
> To draw all this as a tree, I would do it the following way (AVSequencer
> is abbreviated simply lavs):
> lavsContext:
>    1.  list of lavsModule ->
>         1.1. list of lavsSongs (sub-songs)
>    2. list of lavsInstruments (all instruments shared between sub-songs).
>    3. Same for envelopes, etc.
>
> lavsSongs of course descendends to order list and track data.
> lavsInstruments descend to samples, which descend to synths each.

Why not open a new lavsContext per file? That's what libswscale does,
for example. And which structure is BSS in this schematic?

Ronald