diff --git a/include/hardware/camera2.h b/include/hardware/camera2.h
index 8209985..8b789ec 100644
--- a/include/hardware/camera2.h
+++ b/include/hardware/camera2.h
@@ -667,6 +667,48 @@
             uint32_t *max_buffers);
 
     /**
+     * allocate_reprocess_stream_from_stream:
+     *
+     * Allocate a new input stream for use, which will use the buffers allocated
+     * for an existing output stream. That is, after the HAL enqueues a buffer
+     * onto the output stream, it may see that same buffer handed to it from
+     * this input reprocessing stream. After the HAL releases the buffer back to
+     * the reprocessing stream, it will be returned to the output queue for
+     * reuse.
+     *
+     * Error conditions:
+     *
+     * - Using an output stream of unsuitable size/format for the basis of the
+     *   reprocessing stream.
+     *
+     * - Attempting to allocatee too many reprocessing streams at once.
+     *
+     * Input parameters:
+     *
+     * - output_stream_id: The ID of an existing output stream which has
+     *   a size and format suitable for reprocessing.
+     *
+     * - reprocess_stream_ops: A structure of function pointers for acquiring
+     *   and releasing buffers for this stream. The underlying stream will use
+     *   the same graphics buffer handles as the output stream uses.
+     *
+     * Output parameters:
+     *
+     * - stream_id: An unsigned integer identifying this stream. This value is
+     *   used in incoming requests to identify the stream, and in releasing the
+     *   stream. These ids are numbered separately from the input stream ids.
+     *
+     * The HAL client must always release the reprocessing stream before it
+     * releases the output stream it is based on.
+     *
+     */
+    int (*allocate_reprocess_stream_from_stream)(const struct camera2_device *,
+            uint32_t output_stream_id,
+            const camera2_stream_in_ops_t *reprocess_stream_ops,
+            // outputs
+            uint32_t *stream_id);
+
+    /**
      * Release a reprocessing stream. Returns an error if called when
      * get_in_progress_count is non-zero, or if the stream id is not
      * valid.