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Diffstat (limited to 'libmpv2/libmpv2-sys/include/stream_cb.h')
| -rw-r--r-- | libmpv2/libmpv2-sys/include/stream_cb.h | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/libmpv2/libmpv2-sys/include/stream_cb.h b/libmpv2/libmpv2-sys/include/stream_cb.h new file mode 100644 index 0000000..4257b40 --- /dev/null +++ b/libmpv2/libmpv2-sys/include/stream_cb.h @@ -0,0 +1,245 @@ +/* + * yt - A fully featured command line YouTube client + * + * Copyright (C) 2017 the mpv developers + * Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de> + * SPDX-License-Identifier: GPL-3.0-or-later + * + * This file is part of Yt. + * + * You should have received a copy of the License along with this program. + * If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>. + */ + +#ifndef MPV_CLIENT_API_STREAM_CB_H_ +#define MPV_CLIENT_API_STREAM_CB_H_ + +#include "client.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * Warning: this API is not stable yet. + * + * Overview + * -------- + * + * This API can be used to make mpv read from a stream with a custom + * implementation. This interface is inspired by funopen on BSD and + * fopencookie on linux. The stream is backed by user-defined callbacks + * which can implement customized open, read, seek, size and close behaviors. + * + * Usage + * ----- + * + * Register your stream callbacks with the mpv_stream_cb_add_ro() function. You + * have to provide a mpv_stream_cb_open_ro_fn callback to it (open_fn argument). + * + * Once registered, you can `loadfile myprotocol://myfile`. Your open_fn will be + * invoked with the URI and you must fill out the provided mpv_stream_cb_info + * struct. This includes your stream callbacks (like read_fn), and an opaque + * cookie, which will be passed as the first argument to all the remaining + * stream callbacks. + * + * Note that your custom callbacks must not invoke libmpv APIs as that would + * cause a deadlock. (Unless you call a different mpv_handle than the one the + * callback was registered for, and the mpv_handles refer to different mpv + * instances.) + * + * Stream lifetime + * --------------- + * + * A stream remains valid until its close callback has been called. It's up to + * libmpv to call the close callback, and the libmpv user cannot close it + * directly with the stream_cb API. + * + * For example, if you consider your custom stream to become suddenly invalid + * (maybe because the underlying stream died), libmpv will continue using your + * stream. All you can do is returning errors from each callback, until libmpv + * gives up and closes it. + * + * Protocol registration and lifetime + * ---------------------------------- + * + * Protocols remain registered until the mpv instance is terminated. This means + * in particular that it can outlive the mpv_handle that was used to register + * it, but once mpv_terminate_destroy() is called, your registered callbacks + * will not be called again. + * + * Protocol unregistration is finished after the mpv core has been destroyed + * (e.g. after mpv_terminate_destroy() has returned). + * + * If you do not call mpv_terminate_destroy() yourself (e.g. plugin-style code), + * you will have to deal with the registration or even streams outliving your + * code. Here are some possible ways to do this: + * - call mpv_terminate_destroy(), which destroys the core, and will make sure + * all streams are closed once this function returns + * - you refcount all resources your stream "cookies" reference, so that it + * doesn't matter if streams live longer than expected + * - create "cancellation" semantics: after your protocol has been unregistered, + * notify all your streams that are still opened, and make them drop all + * referenced resources - then return errors from the stream callbacks as + * long as the stream is still opened + * + */ + +/** + * Read callback used to implement a custom stream. The semantics of the + * callback match read(2) in blocking mode. Short reads are allowed (you can + * return less bytes than requested, and libmpv will retry reading the rest + * with another call). If no data can be immediately read, the callback must + * block until there is new data. A return of 0 will be interpreted as final + * EOF, although libmpv might retry the read, or seek to a different position. + * + * @param cookie opaque cookie identifying the stream, + * returned from mpv_stream_cb_open_fn + * @param buf buffer to read data into + * @param size of the buffer + * @return number of bytes read into the buffer + * @return 0 on EOF + * @return -1 on error + */ +typedef int64_t (*mpv_stream_cb_read_fn)(void *cookie, char *buf, uint64_t nbytes); + +/** + * Seek callback used to implement a custom stream. + * + * Note that mpv will issue a seek to position 0 immediately after opening. This + * is used to test whether the stream is seekable (since seekability might + * depend on the URI contents, not just the protocol). Return + * MPV_ERROR_UNSUPPORTED if seeking is not implemented for this stream. This + * seek also serves to establish the fact that streams start at position 0. + * + * This callback can be NULL, in which it behaves as if always returning + * MPV_ERROR_UNSUPPORTED. + * + * @param cookie opaque cookie identifying the stream, + * returned from mpv_stream_cb_open_fn + * @param offset target absolute stream position + * @return the resulting offset of the stream + * MPV_ERROR_UNSUPPORTED or MPV_ERROR_GENERIC if the seek failed + */ +typedef int64_t (*mpv_stream_cb_seek_fn)(void *cookie, int64_t offset); + +/** + * Size callback used to implement a custom stream. + * + * Return MPV_ERROR_UNSUPPORTED if no size is known. + * + * This callback can be NULL, in which it behaves as if always returning + * MPV_ERROR_UNSUPPORTED. + * + * @param cookie opaque cookie identifying the stream, + * returned from mpv_stream_cb_open_fn + * @return the total size in bytes of the stream + */ +typedef int64_t (*mpv_stream_cb_size_fn)(void *cookie); + +/** + * Close callback used to implement a custom stream. + * + * @param cookie opaque cookie identifying the stream, + * returned from mpv_stream_cb_open_fn + */ +typedef void (*mpv_stream_cb_close_fn)(void *cookie); + +/** + * Cancel callback used to implement a custom stream. + * + * This callback is used to interrupt any current or future read and seek + * operations. It will be called from a separate thread than the demux + * thread, and should not block. + * + * This callback can be NULL. + * + * Available since API 1.106. + * + * @param cookie opaque cookie identifying the stream, + * returned from mpv_stream_cb_open_fn + */ +typedef void (*mpv_stream_cb_cancel_fn)(void *cookie); + +/** + * See mpv_stream_cb_open_ro_fn callback. + */ +typedef struct mpv_stream_cb_info { + /** + * Opaque user-provided value, which will be passed to the other callbacks. + * The close callback will be called to release the cookie. It is not + * interpreted by mpv. It doesn't even need to be a valid pointer. + * + * The user sets this in the mpv_stream_cb_open_ro_fn callback. + */ + void *cookie; + + /** + * Callbacks set by the user in the mpv_stream_cb_open_ro_fn callback. Some + * of them are optional, and can be left unset. + * + * The following callbacks are mandatory: read_fn, close_fn + */ + mpv_stream_cb_read_fn read_fn; + mpv_stream_cb_seek_fn seek_fn; + mpv_stream_cb_size_fn size_fn; + mpv_stream_cb_close_fn close_fn; + mpv_stream_cb_cancel_fn cancel_fn; /* since API 1.106 */ +} mpv_stream_cb_info; + +/** + * Open callback used to implement a custom read-only (ro) stream. The user + * must set the callback fields in the passed info struct. The cookie field + * also can be set to store state associated to the stream instance. + * + * Note that the info struct is valid only for the duration of this callback. + * You can't change the callbacks or the pointer to the cookie at a later point. + * + * Each stream instance created by the open callback can have different + * callbacks. + * + * The close_fn callback will terminate the stream instance. The pointers to + * your callbacks and cookie will be discarded, and the callbacks will not be + * called again. + * + * @param user_data opaque user data provided via mpv_stream_cb_add() + * @param uri name of the stream to be opened (with protocol prefix) + * @param info fields which the user should fill + * @return 0 on success, MPV_ERROR_LOADING_FAILED if the URI cannot be opened. + */ +typedef int (*mpv_stream_cb_open_ro_fn)(void *user_data, char *uri, + mpv_stream_cb_info *info); + +/** + * Add a custom stream protocol. This will register a protocol handler under + * the given protocol prefix, and invoke the given callbacks if an URI with the + * matching protocol prefix is opened. + * + * The "ro" is for read-only - only read-only streams can be registered with + * this function. + * + * The callback remains registered until the mpv core is registered. + * + * If a custom stream with the same name is already registered, then the + * MPV_ERROR_INVALID_PARAMETER error is returned. + * + * @param protocol protocol prefix, for example "foo" for "foo://" URIs + * @param user_data opaque pointer passed into the mpv_stream_cb_open_fn + * callback. + * @return error code + */ +MPV_EXPORT int mpv_stream_cb_add_ro(mpv_handle *ctx, const char *protocol, void *user_data, + mpv_stream_cb_open_ro_fn open_fn); + +#ifdef MPV_CPLUGIN_DYNAMIC_SYM + +MPV_DEFINE_SYM_PTR(mpv_stream_cb_add_ro) +#define mpv_stream_cb_add_ro pfn_mpv_stream_cb_add_ro + +#endif + +#ifdef __cplusplus +} +#endif + +#endif |