mirror of
https://github.com/mpv-player/mpv
synced 2024-12-21 22:30:22 +00:00
bbfafb5614
The license text refers a "above copyright notice", so I guess it'd be good to actually provide such a notice. Add the license to some files that were missing it (since in theory, our Copyright file says that such files are LGPL by default). Remove the questionable remarks about the license in the client API.
224 lines
8.7 KiB
C
224 lines
8.7 KiB
C
/* Copyright (C) 2017 the mpv developers
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#ifndef MPV_CLIENT_API_STREAM_CB_H_
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#define MPV_CLIENT_API_STREAM_CB_H_
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#include "client.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Warning: this API is not stable yet.
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*
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* Overview
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* --------
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*
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* This API can be used to make mpv read from a stream with a custom
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* implementation. This interface is inspired by funopen on BSD and
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* fopencookie on linux. The stream is backed by user-defined callbacks
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* which can implement customized open, read, seek, size and close behaviors.
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*
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* Usage
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* -----
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*
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* Register your stream callbacks with the mpv_stream_cb_add_ro() function. You
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* have to provide a mpv_stream_cb_open_ro_fn callback to it (open_fn argument).
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*
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* Once registered, you can `loadfile myprotocol://myfile`. Your open_fn will be
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* invoked with the URI and you must fill out the provided mpv_stream_cb_info
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* struct. This includes your stream callbacks (like read_fn), and an opaque
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* cookie, which will be passed as the first argument to all the remaining
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* stream callbacks.
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*
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* Note that your custom callbacks must not invoke libmpv APIs as that would
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* cause a deadlock. (Unless you call a different mpv_handle than the one the
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* callback was registered for, and the mpv_handles refer to different mpv
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* instances.)
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*
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* Stream lifetime
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* ---------------
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*
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* A stream remains valid until its close callback has been called. It's up to
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* libmpv to call the close callback, and the libmpv user cannot close it
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* directly with the stream_cb API.
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*
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* For example, if you consider your custom stream to become suddenly invalid
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* (maybe because the underlying stream died), libmpv will continue using your
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* stream. All you can do is returning errors from each callback, until libmpv
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* gives up and closes it.
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*
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* Protocol registration and lifetime
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* ----------------------------------
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*
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* Protocols remain registered until the mpv instance is terminated. This means
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* in particular that it can outlive the mpv_handle that was used to register
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* it, but once mpv_terminate_destroy() is called, your registered callbacks
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* will not be called again.
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*
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* Protocol unregistration is finished after the mpv core has been destroyed
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* (e.g. after mpv_terminate_destroy() has returned).
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*
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* If you do not call mpv_terminate_destroy() yourself (e.g. plugin-style code),
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* you will have to deal with the registration or even streams outliving your
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* code. Here are some possible ways to do this:
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* - call mpv_terminate_destroy(), which destroys the core, and will make sure
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* all streams are closed once this function returns
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* - you refcount all resources your stream "cookies" reference, so that it
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* doesn't matter if streams live longer than expected
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* - create "cancellation" semantics: after your protocol has been unregistered,
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* notify all your streams that are still opened, and make them drop all
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* referenced resources - then return errors from the stream callbacks as
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* long as the stream is still opened
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*
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*/
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/**
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* Read callback used to implement a custom stream. The semantics of the
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* callback match read(2) in blocking mode. Short reads are allowed (you can
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* return less bytes than requested, and libmpv will retry reading the rest
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* with a nother call). If no data can be immediately read, the callback must
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* block until there is new data. A return of 0 will be interpreted as final
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* EOF, although libmpv might retry the read, or seek to a different position.
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*
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* @param cookie opaque cookie identifying the stream,
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* returned from mpv_stream_cb_open_fn
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* @param buf buffer to read data into
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* @param size of the buffer
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* @return number of bytes read into the buffer
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* @return 0 on EOF
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* @return -1 on error
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*/
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typedef int64_t (*mpv_stream_cb_read_fn)(void *cookie, char *buf, uint64_t nbytes);
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/**
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* Seek callback used to implement a custom stream.
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*
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* Note that mpv will issue a seek to position 0 immediately after opening. This
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* is used to test whether the stream is seekable (since seekability might
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* depend on the URI contents, not just the protocol). Return
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* MPV_ERROR_UNSUPPORTED if seeking is not implemented for this stream. This
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* seek also servies to establish the fact that streams start at position 0.
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*
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* This callback can be NULL, in which it behaves as if always returning
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* MPV_ERROR_UNSUPPORTED.
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*
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* @param cookie opaque cookie identifying the stream,
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* returned from mpv_stream_cb_open_fn
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* @param offset target absolut stream position
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* @return the resulting offset of the stream
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* MPV_ERROR_UNSUPPORTED or MPV_ERROR_GENERIC if the seek failed
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*/
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typedef int64_t (*mpv_stream_cb_seek_fn)(void *cookie, int64_t offset);
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/**
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* Size callback used to implement a custom stream.
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*
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* Return MPV_ERROR_UNSUPPORTED if no size is known.
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*
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* This callback can be NULL, in which it behaves as if always returning
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* MPV_ERROR_UNSUPPORTED.
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*
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* @param cookie opaque cookie identifying the stream,
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* returned from mpv_stream_cb_open_fn
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* @return the total size in bytes of the stream
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*/
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typedef int64_t (*mpv_stream_cb_size_fn)(void *cookie);
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/**
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* Close callback used to implement a custom stream.
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*
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* @param cookie opaque cookie identifying the stream,
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* returned from mpv_stream_cb_open_fn
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*/
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typedef void (*mpv_stream_cb_close_fn)(void *cookie);
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/**
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* See mpv_stream_cb_open_ro_fn callback.
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*/
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typedef struct mpv_stream_cb_info {
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/**
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* Opaque user-provided value, which will be passed to the other callbacks.
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* The close callback will be called to release the cookie. It is not
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* interpreted by mpv. It doesn't even need to be a valid pointer.
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*
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* The user sets this in the mpv_stream_cb_open_ro_fn callback.
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*/
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void *cookie;
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/**
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* Callbacks set by the user in the mpv_stream_cb_open_ro_fn callback. Some
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* of them are optional, and can be left unset.
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*
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* The following callbacks are mandatory: read_fn, close_fn
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*/
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mpv_stream_cb_read_fn read_fn;
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mpv_stream_cb_seek_fn seek_fn;
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mpv_stream_cb_size_fn size_fn;
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mpv_stream_cb_close_fn close_fn;
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} mpv_stream_cb_info;
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/**
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* Open callback used to implement a custom read-only (ro) stream. The user
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* must set the callback fields in the passed info struct. The cookie field
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* also can be set to store state associated to the stream instance.
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*
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* Note that the info struct is valid only for the duration of this callback.
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* You can't change the callbacks or the pointer to the cookie at a later point.
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*
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* Each stream instance created by the open callback can have different
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* callbacks.
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*
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* The close_fn callback will terminate the stream instance. The pointers to
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* your callbacks and cookie will be discarded, and the callbacks will not be
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* called again.
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*
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* @param user_data opaque user data provided via mpv_stream_cb_add()
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* @param uri name of the stream to be opened (with protocol prefix)
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* @param info fields which the user should fill
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* @return 0 on success, MPV_ERROR_LOADING_FAILED if the URI cannot be opened.
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*/
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typedef int (*mpv_stream_cb_open_ro_fn)(void *user_data, char *uri,
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mpv_stream_cb_info *info);
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/**
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* Add a custom stream protocol. This will register a protocol handler under
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* the given protocol prefix, and invoke the given callbacks if an URI with the
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* matching protocol prefix is opened.
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*
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* The "ro" is for read-only - only read-only streams can be registered with
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* this function.
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*
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* The callback remains registered until the mpv core is registered.
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*
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* If a custom stream with the same name is already registered, then the
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* MPV_ERROR_INVALID_PARAMETER error is returned.
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*
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* @param protocol protocol prefix, for example "foo" for "foo://" URIs
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* @param user_data opaque pointer passed into the mpv_stream_cb_open_fn
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* callback.
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* @return error code
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*/
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int mpv_stream_cb_add_ro(mpv_handle *ctx, const char *protocol, void *user_data,
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mpv_stream_cb_open_ro_fn open_fn);
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#ifdef __cplusplus
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}
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#endif
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#endif
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