avformat/dashdec: add dash demuxer base version

[ffmpeg] / libavformat / avio.h

diff --git a/libavformat/avio.h b/libavformat/avio.h
index 525eb7129eb5b5a5a2a8dc015275526b9b25a0cb..f9c5972adae65d47d29a5cdc9c186694b1ce5f2f 100644 (file)
--- a/libavformat/avio.h
+++ b/libavformat/avio.h
@@ -137,7 +137,13 @@ enum AVIODataMarkerType {
      * Trailer data, which doesn't contain actual content, but only for
      * finalizing the output file.
      */
-    AVIO_DATA_MARKER_TRAILER
+    AVIO_DATA_MARKER_TRAILER,
+    /**
+     * A point in the output bytestream where the underlying AVIOContext might
+     * flush the buffer depending on latency or buffering requirements. Typically
+     * means the end of a packet.
+     */
+    AVIO_DATA_MARKER_FLUSH_POINT,
 };
 
 /**
@@ -168,8 +174,9 @@ typedef struct AVIOContext {
     const AVClass *av_class;
 
     /*
-     * The following shows the relationship between buffer, buf_ptr, buf_end, buf_size,
-     * and pos, when reading and when writing (since AVIOContext is used for both):
+     * The following shows the relationship between buffer, buf_ptr,
+     * buf_ptr_max, buf_end, buf_size, and pos, when reading and when writing
+     * (since AVIOContext is used for both):
      *
      **********************************************************************************
      *                                   READING
@@ -196,21 +203,24 @@ typedef struct AVIOContext {
      *                                   WRITING
      **********************************************************************************
      *
-     *                                          |          buffer_size          |
-     *                                          |-------------------------------|
-     *                                          |                               |
+     *                             |          buffer_size                 |
+     *                             |--------------------------------------|
+     *                             |                                      |
      *
-     *                                       buffer              buf_ptr     buf_end
-     *                                          +-------------------+-----------+
-     *                                          |/ / / / / / / / / /|           |
-     *  write buffer:                           | / to be flushed / |           |
-     *                                          |/ / / / / / / / / /|           |
-     *                                          +-------------------+-----------+
+     *                                                buf_ptr_max
+     *                          buffer                 (buf_ptr)       buf_end
+     *                             +-----------------------+--------------+
+     *                             |/ / / / / / / / / / / /|              |
+     *  write buffer:              | / / to be flushed / / |              |
+     *                             |/ / / / / / / / / / / /|              |
+     *                             +-----------------------+--------------+
+     *                               buf_ptr can be in this
+     *                               due to a backward seek
      *
-     *                                         pos
-     *               +--------------------------+-----------------------------------+
-     *  output file: |                          |                                   |
-     *               +--------------------------+-----------------------------------+
+     *                            pos
+     *               +-------------+----------------------------------------------+
+     *  output file: |             |                                              |
+     *               +-------------+----------------------------------------------+
      *
      */
     unsigned char *buffer;  /**< Start of the buffer. */
@@ -226,7 +236,7 @@ typedef struct AVIOContext {
     int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
     int64_t (*seek)(void *opaque, int64_t offset, int whence);
     int64_t pos;            /**< position in the file of the current buffer */
-    int must_flush;         /**< true if the next seek should flush */
+    int must_flush;         /**< unused */
     int eof_reached;        /**< true if eof reached */
     int write_flag;         /**< true if open for writing */
     int max_packet_size;
@@ -329,6 +339,17 @@ typedef struct AVIOContext {
     int (*short_seek_get)(void *opaque);
 
     int64_t written;
+
+    /**
+     * Maximum reached position before a backward seek in the write buffer,
+     * used keeping track of already written data for a later flush.
+     */
+    unsigned char *buf_ptr_max;
+
+    /**
+     * Try to buffer at least this amount of data before flushing it
+     */
+    int min_packet_size;
 } AVIOContext;
 
 /**
@@ -418,7 +439,7 @@ void avio_free_directory_entry(AVIODirEntry **entry);
 
 /**
  * Allocate and initialize an AVIOContext for buffered I/O. It must be later
- * freed with av_free().
+ * freed with avio_context_free().
  *
  * @param buffer Memory block for input/output operations via AVIOContext.
  *        The buffer must be allocated with av_malloc() and friends.
@@ -446,6 +467,14 @@ AVIOContext *avio_alloc_context(
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
                   int64_t (*seek)(void *opaque, int64_t offset, int whence));
 
+/**
+ * Free the supplied IO context and everything associated with it.
+ *
+ * @param s Double pointer to the IO context. This function will write NULL
+ * into s.
+ */
+void avio_context_free(AVIOContext **s);
+
 void avio_w8(AVIOContext *s, int b);
 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
 void avio_wl64(AVIOContext *s, uint64_t val);
@@ -569,6 +598,15 @@ void avio_flush(AVIOContext *s);
  */
 int avio_read(AVIOContext *s, unsigned char *buf, int size);
 
+/**
+ * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed
+ * to read fewer bytes than requested. The missing bytes can be read in the next
+ * call. This always tries to read at least 1 byte.
+ * Useful to reduce latency in certain cases.
+ * @return number of bytes read or AVERROR
+ */
+int avio_read_partial(AVIOContext *s, unsigned char *buf, int size);
+
 /**
  * @name Functions for reading from AVIOContext
  * @{