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adapter: update some docs

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This commit is contained in:
Wim Taymans 2009-05-13 18:50:23 +02:00
parent f6d71be830
commit 763a6f6761
1 changed files with 20 additions and 5 deletions
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25
libs/gst/base/gstadapter.c
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@ -36,6 +36,10 @@
* in chunks of the desired size using gst_adapter_peek(). After the data is * in chunks of the desired size using gst_adapter_peek(). After the data is
* processed, it is freed using gst_adapter_flush(). * processed, it is freed using gst_adapter_flush().
* *
* Other methods such as gst_adapter_take() and gst_adapter_take_buffer()
* combine gst_adapter_peek() and gst_adapter_flush() in one method and are
* potentially more convenient for some use cases.
*
* For example, a sink pad's chain function that needs to pass data to a library * For example, a sink pad's chain function that needs to pass data to a library
* in 512-byte chunks could be implemented like this: * in 512-byte chunks could be implemented like this:
* <programlisting> * <programlisting>
@ -74,11 +78,22 @@
* Also check the GST_BUFFER_FLAG_DISCONT flag on the buffer. Some elements might * Also check the GST_BUFFER_FLAG_DISCONT flag on the buffer. Some elements might
* need to clear the adapter after a discontinuity. * need to clear the adapter after a discontinuity.
* *
* Since 0.10.24, the adapter will keep track of the timestamps of the buffers
* that were pushed. The last seen timestamp before the current position
* can be queried with gst_adapter_prev_timestamp(). This function can
* optionally return the amount of bytes between the start of the buffer that
* carried the timestamp and the current adapter position. The distance is
* useful when dealing with, for example, raw audio samples because it allows
* you to calculate the timestamp of the current adapter position by using the
* last seen timestamp and the amount of bytes since.
*
* A last thing to note is that while GstAdapter is pretty optimized, * A last thing to note is that while GstAdapter is pretty optimized,
* merging buffers still might be an operation that requires a memcpy() * merging buffers still might be an operation that requires a malloc() and
* operation, and this operation is not the fastest. Because of this, some * memcpy() operation, and these operations are not the fastest. Because of
* functions like gst_adapter_available_fast() are provided to help speed up * this, some functions like gst_adapter_available_fast() are provided to help
* such cases should you want to. * speed up such cases should you want to. To avoid repeated memory allocations,
* gst_adapter_copy() can be used to copy data into a (statically allocated)
* user provided buffer.
* *
* GstAdapter is not MT safe. All operations on an adapter must be serialized by * GstAdapter is not MT safe. All operations on an adapter must be serialized by
* the caller. This is not normally a problem, however, as the normal use case * the caller. This is not normally a problem, however, as the normal use case
@ -90,7 +105,7 @@
* access the buffer later. The adapter will never modify the data in the * access the buffer later. The adapter will never modify the data in the
* buffer pushed in it. * buffer pushed in it.
* *
* Last reviewed on 2006-04-04 (0.10.6). * Last reviewed on 2009-05-13 (0.10.24).
*/ */