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651061dfd9
Original commit message from CVS: * libs/gst/base/gsttypefindhelper.c: (buf_helper_find_peek): Fix off-by-one bug that would only allow peeks of N-1 bytes from the start even if the buffer to typefind on contains in fact N bytes of data (makes vorbis typefinding from a vorbis identification header buffer work). * tests/check/Makefile.am: * tests/check/libs/.cvsignore: * tests/check/libs/typefindhelper.c: (GST_START_TEST), (gst_typefindhelper_suite), (main), (foobar_typefind), (plugin_init): Add very basic unit test for gst_type_find_helper_for_buffer() that checks for the problem fixed above.
398 lines
12 KiB
C
398 lines
12 KiB
C
/* GStreamer
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* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
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* Copyright (C) 2000,2005 Wim Taymans <wim@fluendo.com>
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* Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>
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*
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* gsttypefindhelper.c:
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:gsttypefindhelper
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* @short_description: Utility functions for typefinding
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*
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* Utility functions for elements doing typefinding:
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* gst_type_find_helper() does typefinding in pull mode, while
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* gst_type_find_helper_for_buffer() is useful for elements needing to do
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* typefinding in push mode from a chain function.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include "gsttypefindhelper.h"
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static gint
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type_find_factory_rank_cmp (gconstpointer fac1, gconstpointer fac2)
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{
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if (GST_PLUGIN_FEATURE (fac1)->rank != GST_PLUGIN_FEATURE (fac2)->rank)
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return GST_PLUGIN_FEATURE (fac2)->rank - GST_PLUGIN_FEATURE (fac1)->rank;
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/* to make the order in which things happen more deterministic,
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* sort by name when the ranks are the same. */
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return strcmp (GST_PLUGIN_FEATURE_NAME (fac1),
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GST_PLUGIN_FEATURE_NAME (fac2));
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}
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/* ********************** typefinding in pull mode ************************ */
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typedef struct
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{
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guint best_probability;
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GstCaps *caps;
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guint64 size;
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GSList *buffers;
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GstTypeFindFactory *factory;
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GstTypeFindHelperGetRangeFunction func;
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GstObject *obj;
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}
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GstTypeFindHelper;
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static guint8 *
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helper_find_peek (gpointer data, gint64 offset, guint size)
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{
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GstTypeFindHelper *find;
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GstBuffer *buffer;
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GstFlowReturn ret;
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find = (GstTypeFindHelper *) data;
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GST_LOG_OBJECT (find->obj, "'%s' called peek (%" G_GINT64_FORMAT
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", %u)", GST_PLUGIN_FEATURE_NAME (find->factory), offset, size);
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if (size == 0)
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return NULL;
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if (offset < 0) {
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if (find->size == -1 || find->size < -offset)
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return NULL;
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offset += find->size;
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}
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/* see if we have a matching buffer already in our list */
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if (size > 0) {
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GSList *walk;
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for (walk = find->buffers; walk; walk = walk->next) {
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GstBuffer *buf = GST_BUFFER_CAST (walk->data);
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guint64 buf_offset = GST_BUFFER_OFFSET (buf);
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guint buf_size = GST_BUFFER_SIZE (buf);
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if (buf_offset <= offset && (offset + size) < (buf_offset + buf_size))
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return GST_BUFFER_DATA (buf) + (offset - buf_offset);
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}
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}
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buffer = NULL;
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ret = find->func (find->obj, offset, size, &buffer);
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if (ret != GST_FLOW_OK)
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goto error;
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/* getrange might silently return shortened buffers at the end of a file,
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* we must, however, always return either the full requested data or NULL */
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if (GST_BUFFER_OFFSET (buffer) != offset || GST_BUFFER_SIZE (buffer) < size) {
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GST_DEBUG ("droping short buffer: %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT
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" instead of %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT,
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GST_BUFFER_OFFSET (buffer), GST_BUFFER_OFFSET (buffer) +
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GST_BUFFER_SIZE (buffer) - 1, offset, offset + size - 1);
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gst_buffer_unref (buffer);
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return NULL;
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}
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find->buffers = g_slist_prepend (find->buffers, buffer);
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return GST_BUFFER_DATA (buffer);
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error:
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{
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return NULL;
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}
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}
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static void
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helper_find_suggest (gpointer data, guint probability, const GstCaps * caps)
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{
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GstTypeFindHelper *find = (GstTypeFindHelper *) data;
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GST_LOG_OBJECT (find->obj,
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"'%s' called called suggest (%u, %" GST_PTR_FORMAT ")",
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GST_PLUGIN_FEATURE_NAME (find->factory), probability, caps);
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if (probability > find->best_probability) {
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GstCaps *copy = gst_caps_copy (caps);
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gst_caps_replace (&find->caps, copy);
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gst_caps_unref (copy);
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find->best_probability = probability;
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}
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}
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static guint64
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helper_find_get_length (gpointer data)
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{
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GstTypeFindHelper *find = (GstTypeFindHelper *) data;
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GST_LOG_OBJECT (find->obj, "'%s' called called get_length, returning %"
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G_GUINT64_FORMAT, GST_PLUGIN_FEATURE_NAME (find->factory), find->size);
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return find->size;
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}
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/**
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* gst_type_find_helper_get_range:
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* @obj: A #GstObject that will be passed as first argument to @func
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* @func: A generic #GstTypeFindHelperGetRangeFunction that will be used
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* to access data at random offsets when doing the typefinding
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* @size: The length in bytes
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* @prob: location to store the probability of the found caps, or #NULL
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*
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* Utility function to do pull-based typefinding. Unlike gst_type_find_helper()
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* however, this function will use the specified function @func to obtain the
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* data needed by the typefind functions, rather than operating on a given
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* source pad. This is useful mostly for elements like tag demuxers which
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* strip off data at the beginning and/or end of a file and want to typefind
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* the stripped data stream before adding their own source pad (the specified
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* callback can then call the upstream peer pad with offsets adjusted for the
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* tag size, for example).
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*
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* Returns: The #GstCaps corresponding to the data stream.
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* Returns #NULL if no #GstCaps matches the data stream.
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*/
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GstCaps *
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gst_type_find_helper_get_range (GstObject * obj,
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GstTypeFindHelperGetRangeFunction func, guint64 size,
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GstTypeFindProbability * prob)
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{
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GstTypeFind gst_find;
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GstTypeFindHelper find;
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GSList *l;
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GList *walk, *type_list = NULL;
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GstCaps *result = NULL;
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g_return_val_if_fail (GST_IS_OBJECT (obj), NULL);
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g_return_val_if_fail (func != NULL, NULL);
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type_list = gst_type_find_factory_get_list ();
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type_list = g_list_sort (type_list, type_find_factory_rank_cmp);
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find.best_probability = 0;
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find.caps = NULL;
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find.size = size;
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find.buffers = NULL;
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find.func = func;
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find.obj = obj;
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gst_find.data = &find;
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gst_find.peek = helper_find_peek;
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gst_find.suggest = helper_find_suggest;
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if (size == 0 || size == (guint64) - 1) {
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gst_find.get_length = NULL;
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} else {
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gst_find.get_length = helper_find_get_length;
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}
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walk = type_list;
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while (walk) {
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GstTypeFindFactory *factory = GST_TYPE_FIND_FACTORY (walk->data);
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find.factory = factory;
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gst_type_find_factory_call_function (factory, &gst_find);
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if (find.best_probability >= GST_TYPE_FIND_MAXIMUM)
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break;
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walk = g_list_next (walk);
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}
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gst_plugin_feature_list_free (type_list);
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if (find.best_probability > 0)
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result = find.caps;
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for (l = find.buffers; l; l = l->next)
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gst_buffer_unref (GST_BUFFER_CAST (l->data));
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g_slist_free (find.buffers);
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if (prob)
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*prob = find.best_probability;
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GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",
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result, (guint) find.best_probability);
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return result;
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}
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/**
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* gst_type_find_helper:
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* @src: A source #GstPad
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* @size: The length in bytes
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*
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* Tries to find what type of data is flowing from the given source #GstPad.
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*
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* Returns: The #GstCaps corresponding to the data stream.
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* Returns #NULL if no #GstCaps matches the data stream.
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*/
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GstCaps *
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gst_type_find_helper (GstPad * src, guint64 size)
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{
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GstTypeFindHelperGetRangeFunction func;
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g_return_val_if_fail (GST_IS_OBJECT (src), NULL);
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g_return_val_if_fail (GST_PAD_GETRANGEFUNC (src) != NULL, NULL);
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func = (GstTypeFindHelperGetRangeFunction) (GST_PAD_GETRANGEFUNC (src));
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return gst_type_find_helper_get_range (GST_OBJECT (src), func, size, NULL);
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}
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/* ********************** typefinding for buffers ************************* */
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typedef struct
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{
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guint8 *data;
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guint size;
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guint best_probability;
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GstCaps *caps;
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GstObject *factory; /* for logging */
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GstObject *obj; /* for logging */
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} GstTypeFindBufHelper;
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static guint8 *
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buf_helper_find_peek (gpointer data, gint64 off, guint size)
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{
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GstTypeFindBufHelper *helper;
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helper = (GstTypeFindBufHelper *) data;
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GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT ", %u)",
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GST_PLUGIN_FEATURE_NAME (helper->factory), off, size);
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if (size == 0)
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return NULL;
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if (off < 0) {
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GST_LOG_OBJECT (helper->obj, "'%s' wanted to peek at end; not supported",
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GST_PLUGIN_FEATURE_NAME (helper->factory));
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return NULL;
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}
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if ((off + size) <= helper->size)
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return helper->data + off;
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return NULL;
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}
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static void
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buf_helper_find_suggest (gpointer data, guint prob, const GstCaps * caps)
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{
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GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data;
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GST_LOG_OBJECT (helper->obj,
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"'%s' called called suggest (%u, %" GST_PTR_FORMAT ")",
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GST_PLUGIN_FEATURE_NAME (helper->factory), prob, caps);
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/* Note: not >= as we call typefinders in order of rank, highest first */
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if (prob > helper->best_probability) {
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GstCaps *copy = gst_caps_copy (caps);
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gst_caps_replace (&helper->caps, copy);
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gst_caps_unref (copy);
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helper->best_probability = prob;
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}
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}
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/**
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* gst_type_find_helper_for_buffer:
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* @obj: object doing the typefinding, or NULL (used for logging)
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* @buf: a #GstBuffer with data to typefind
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* @prob: location to store the probability of the found caps, or #NULL
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*
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* Tries to find what type of data is contained in the given #GstBuffer, the
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* assumption being that the buffer represents the beginning of the stream or
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* file.
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*
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* All available typefinders will be called on the data in order of rank. If
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* a typefinding function returns a probability of #GST_TYPE_FIND_MAXIMUM,
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* typefinding is stopped immediately and the found caps will be returned
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* right away. Otherwise, all available typefind functions will the tried,
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* and the caps with the highest probability will be returned, or #NULL if
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* the content of the buffer could not be identified.
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*
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* Returns: The #GstCaps corresponding to the data, or #NULL if no type could
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* be found. The caller should free the caps returned with gst_caps_unref().
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*/
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GstCaps *
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gst_type_find_helper_for_buffer (GstObject * obj, GstBuffer * buf,
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GstTypeFindProbability * prob)
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{
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GstTypeFindBufHelper helper;
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GstTypeFind find;
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GList *l, *type_list;
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g_return_val_if_fail (buf != NULL, NULL);
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g_return_val_if_fail (GST_IS_BUFFER (buf), NULL);
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g_return_val_if_fail (GST_BUFFER_OFFSET (buf) == 0 ||
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GST_BUFFER_OFFSET (buf) == GST_BUFFER_OFFSET_NONE, NULL);
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helper.data = GST_BUFFER_DATA (buf);
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helper.size = GST_BUFFER_SIZE (buf);
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helper.best_probability = 0;
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helper.caps = NULL;
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helper.obj = obj;
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if (helper.data == NULL || helper.size == 0)
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return NULL;
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find.data = &helper;
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find.peek = buf_helper_find_peek;
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find.suggest = buf_helper_find_suggest;
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find.get_length = NULL;
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type_list = gst_type_find_factory_get_list ();
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type_list = g_list_sort (type_list, type_find_factory_rank_cmp);
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for (l = type_list; l != NULL; l = l->next) {
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GstTypeFindFactory *factory = GST_TYPE_FIND_FACTORY (l->data);
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helper.factory = GST_OBJECT (factory);
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gst_type_find_factory_call_function (factory, &find);
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if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)
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break;
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}
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gst_plugin_feature_list_free (type_list);
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if (helper.best_probability == 0)
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return NULL;
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if (prob)
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*prob = helper.best_probability;
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GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",
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helper.caps, (guint) helper.best_probability);
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return helper.caps;
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}
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