On Wed, Jun 16, 2010 at 10:47:03PM +0300, Martin Storsjö wrote: > On Wed, 16 Jun 2010, Michael Niedermayer wrote: > > > On Wed, Jun 16, 2010 at 07:51:32PM +0300, Martin Storsjö wrote: > > > On Wed, 16 Jun 2010, Michael Niedermayer wrote: > > > > > > > On Mon, Jun 14, 2010 at 08:12:30PM +0300, Martin Storsjö wrote: > > > > > > > > > > Additionally, as far as I've understood AVOptions, they can only set > > > > > something within one struct, since it simply uses offsets. For this > > > > > case, > > > > > we'd need AVOptions that would only apply if the URLContext happens > > > > > to be > > > > > a HTTP context, and then set the options within the priv_data, which > > > > > can't > > > > > be done as a simple offset (unless the priv_data is tacked on at the > > > > > end of the context...) > > > > > > > > I think we should check the past discussion about using AVOptions and > > > > private > > > > contexts. but from memory > > > > Adding an AVClass pointer to URLProtocol (and a priv_data_size of > > > > course too) > > > > allows us to allocate and init to defaults the private context in > > > > generic code > > > > > > Not as far as I understand it. In libavcodec/opt.c, for example > > > av_set_number2, lines 63-70, store values using this logic: > > > > > > dst= ((uint8_t*)obj) + o->offset; > > > *(int*)dst= llrint(num/den)*intnum; > > > > > > So the only things it can express are storing values with a plain offset > > > from the start of the object. There's no code for dereferencing the > > > priv_data pointer and using that as an object. > > > > > > In order to set values within the private data, we'd need to make the > > > private data an AVClass so that it can have different options depending > > > on > > > what the actual protocol is. Then in the generic AVClass for URLContext, > > > we'd need to store the offset of the private data pointer, so that the > > > generic AVOption code can check for options in the private data if the > > > option wasn't found in the generic URLContext. > > > > The user code that calls av_set_number2() can just check if it failed and > > callit on priv_data > > not saying this is better, iam just saying that the extension you hint at is > > not strictly needed > > Hmm, true, that would perhaps simplify things a bit. But even then, we'd > need a way to know whether priv_data actually contains an AVClass or not. > Either we'd mandate such a member for all protocols' priv_data, or add > some flag somewhere in URLContext, e.g. priv_data_has_class.
id mandate it but allow it to be NULL [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Its not that you shouldnt use gotos but rather that you should write readable code and code with gotos often but not always is less readable
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