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647 lines
20 KiB
C
647 lines
20 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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/* ********************** typefinding in pull mode ************************ */
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static void
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helper_find_suggest (gpointer data, guint probability, const GstCaps * caps);
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typedef struct
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{
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GSList *buffers; /* buffer cache */
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guint64 size;
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guint64 last_offset;
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GstTypeFindHelperGetRangeFunction func;
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GstTypeFindProbability best_probability;
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GstCaps *caps;
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GstTypeFindFactory *factory; /* for logging */
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GstObject *obj; /* for logging */
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GstObject *parent;
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} GstTypeFindHelper;
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/*
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* helper_find_peek:
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* @data: helper data struct
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* @off: stream offset
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* @size: block size
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*
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* Get data pointer within a stream. Keeps a cache of read buffers (partly
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* for performance reasons, but mostly because pointers returned by us need
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* to stay valid until typefinding has finished)
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*
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* Returns: address of the data or %NULL if buffer does not cover the
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* requested range.
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*/
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static const guint8 *
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helper_find_peek (gpointer data, gint64 offset, guint size)
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{
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GstTypeFindHelper *helper;
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GstBuffer *buffer;
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GstFlowReturn ret;
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GSList *insert_pos = NULL;
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gsize buf_size;
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guint64 buf_offset;
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GstMapInfo info;
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#if 0
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GstCaps *caps;
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#endif
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helper = (GstTypeFindHelper *) data;
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GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT
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", %u)", GST_OBJECT_NAME (helper->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 (helper->size == -1 || helper->size < -offset)
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return NULL;
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offset += helper->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 && offset <= helper->last_offset) {
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GSList *walk;
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for (walk = helper->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_get_size (buf);
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/* buffers are kept sorted by end offset (highest first) in the list, so
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* at this point we save the current position and stop searching if
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* we're after the searched end offset */
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if (buf_offset <= offset) {
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if ((offset + size) < (buf_offset + buf_size)) {
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/* FIXME, unmap after usage */
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if (!gst_buffer_map (buf, &info, GST_MAP_READ))
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return NULL;
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return (guint8 *) info.data + (offset - buf_offset);
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}
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} else if (offset + size >= buf_offset + buf_size) {
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insert_pos = walk;
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break;
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}
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}
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}
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buffer = NULL;
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/* some typefinders go in 1 byte steps over 1k of data and request
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* small buffers. It is really inefficient to pull each time, and pulling
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* a larger chunk is almost free. Trying to pull a larger chunk at the end
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* of the file is also not a problem here, we'll just get a truncated buffer
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* in that case (and we'll have to double-check the size we actually get
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* anyway, see below) */
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ret =
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helper->func (helper->obj, helper->parent, offset, MAX (size, 4096),
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&buffer);
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if (ret != GST_FLOW_OK)
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goto error;
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#if 0
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caps = GST_BUFFER_CAPS (buffer);
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if (caps && !gst_caps_is_empty (caps) && !gst_caps_is_any (caps)) {
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GST_DEBUG ("buffer has caps %" GST_PTR_FORMAT ", suggest max probability",
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caps);
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gst_caps_replace (&helper->caps, caps);
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helper->best_probability = GST_TYPE_FIND_MAXIMUM;
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gst_buffer_unref (buffer);
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return NULL;
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}
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#endif
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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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buf_offset = GST_BUFFER_OFFSET (buffer);
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buf_size = gst_buffer_get_size (buffer);
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if ((buf_offset != -1 && buf_offset != offset) || buf_size < size) {
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GST_DEBUG ("dropping short buffer: %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT
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" instead of %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT,
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buf_offset, buf_offset + buf_size - 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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if (insert_pos) {
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helper->buffers =
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g_slist_insert_before (helper->buffers, insert_pos, buffer);
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} else {
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/* if insert_pos is not set, our offset is bigger than the largest offset
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* we have so far; since we keep the list sorted with highest offsets
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* first, we need to prepend the buffer to the list */
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helper->last_offset = GST_BUFFER_OFFSET (buffer) + buf_size;
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helper->buffers = g_slist_prepend (helper->buffers, buffer);
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}
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/* FIXME, unmap */
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gst_buffer_map (buffer, &info, GST_MAP_READ);
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return info.data;
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error:
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{
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GST_INFO ("typefind function returned: %s", gst_flow_get_name (ret));
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return NULL;
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}
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}
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/*
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* helper_find_suggest:
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* @data: helper data struct
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* @probability: probability of the match
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* @caps: caps of the type
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*
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* If given @probability is higher, replace previously store caps.
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*/
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static void
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helper_find_suggest (gpointer data, GstTypeFindProbability probability,
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const GstCaps * caps)
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{
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GstTypeFindHelper *helper = (GstTypeFindHelper *) data;
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GST_LOG_OBJECT (helper->obj,
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"'%s' called suggest (%u, %" GST_PTR_FORMAT ")",
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GST_OBJECT_NAME (helper->factory), probability, caps);
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if (probability > helper->best_probability) {
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GstCaps *copy = gst_caps_copy (caps);
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gst_caps_take (&helper->caps, copy);
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helper->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 *helper = (GstTypeFindHelper *) data;
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GST_LOG_OBJECT (helper->obj, "'%s' called get_length, returning %"
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G_GUINT64_FORMAT, GST_OBJECT_NAME (helper->factory), helper->size);
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return helper->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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* @parent: the parent of @obj or NULL
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* @func: (scope call): A generic #GstTypeFindHelperGetRangeFunction that will
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* be used to access data at random offsets when doing the typefinding
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* @size: The length in bytes
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* @extension: extension of the media
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* @prob: (out) (allow-none): location to store the probability of the found
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* 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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* When @extension is not NULL, this function will first try the typefind
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* functions for the given extension, which might speed up the typefinding
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* in many cases.
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*
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* Free-function: gst_caps_unref
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*
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* Returns: (transfer full): 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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* Since: 0.10.26
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*/
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GstCaps *
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gst_type_find_helper_get_range (GstObject * obj, GstObject * parent,
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GstTypeFindHelperGetRangeFunction func, guint64 size,
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const gchar * extension, GstTypeFindProbability * prob)
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{
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GstTypeFindHelper helper;
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GstTypeFind find;
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GSList *walk;
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GList *l, *type_list;
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GstCaps *result = NULL;
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gint pos = 0;
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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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helper.buffers = NULL;
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helper.size = size;
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helper.last_offset = 0;
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helper.func = func;
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helper.best_probability = GST_TYPE_FIND_NONE;
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helper.caps = NULL;
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helper.obj = obj;
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helper.parent = parent;
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find.data = &helper;
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find.peek = helper_find_peek;
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find.suggest = helper_find_suggest;
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if (size == 0 || size == (guint64) - 1) {
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find.get_length = NULL;
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} else {
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find.get_length = helper_find_get_length;
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}
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type_list = gst_type_find_factory_get_list ();
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/* move the typefinders for the extension first in the list. The idea is that
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* when one of them returns MAX we don't need to search further as there is a
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* very high chance we got the right type. */
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if (extension) {
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GList *next;
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GST_LOG_OBJECT (obj, "sorting typefind for extension %s to head",
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extension);
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for (l = type_list; l; l = next) {
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GstTypeFindFactory *factory;
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gint i;
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gchar **ext;
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next = l->next;
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factory = GST_TYPE_FIND_FACTORY (l->data);
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ext = gst_type_find_factory_get_extensions (factory);
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if (ext == NULL)
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continue;
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GST_LOG_OBJECT (obj, "testing factory %s for extension %s",
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GST_OBJECT_NAME (factory), extension);
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for (i = 0; ext[i]; i++) {
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if (strcmp (ext[i], extension) == 0) {
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/* found extension, move in front */
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GST_LOG_OBJECT (obj, "moving typefind for extension %s to head",
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extension);
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/* remove entry from list */
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type_list = g_list_delete_link (type_list, l);
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/* insert at the position */
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type_list = g_list_insert (type_list, factory, pos);
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/* next element will be inserted after this one */
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pos++;
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break;
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}
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}
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}
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}
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for (l = type_list; l; l = l->next) {
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helper.factory = GST_TYPE_FIND_FACTORY (l->data);
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gst_type_find_factory_call_function (helper.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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for (walk = helper.buffers; walk; walk = walk->next)
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gst_buffer_unref (GST_BUFFER_CAST (walk->data));
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g_slist_free (helper.buffers);
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if (helper.best_probability > 0)
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result = helper.caps;
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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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result, (guint) helper.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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* Free-function: gst_caps_unref
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*
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* Returns: (transfer full): 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),
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GST_OBJECT_PARENT (src), func, size, NULL, 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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const guint8 *data; /* buffer data */
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gsize size;
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GstTypeFindProbability best_probability;
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GstCaps *caps;
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GstTypeFindFactory *factory; /* for logging */
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GstObject *obj; /* for logging */
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} GstTypeFindBufHelper;
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/*
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* buf_helper_find_peek:
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* @data: helper data struct
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* @off: stream offset
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* @size: block size
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*
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* Get data pointer within a buffer.
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*
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* Returns: address inside the buffer or %NULL if buffer does not cover the
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* requested range.
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*/
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static const 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_OBJECT_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_OBJECT_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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/*
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* buf_helper_find_suggest:
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* @data: helper data struct
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* @probability: probability of the match
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* @caps: caps of the type
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*
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* If given @probability is higher, replace previously store caps.
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*/
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static void
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buf_helper_find_suggest (gpointer data, GstTypeFindProbability probability,
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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 suggest (%u, %" GST_PTR_FORMAT ")",
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GST_OBJECT_NAME (helper->factory), probability, caps);
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/* Note: not >= as we call typefinders in order of rank, highest first */
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if (probability > 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 = probability;
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}
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}
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/**
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* gst_type_find_helper_for_data:
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* @obj: object doing the typefinding, or NULL (used for logging)
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* @data: (in) (transfer none): a pointer with data to typefind
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* @size: (in) (transfer none): the size of @data
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* @prob: (out) (allow-none): location to store the probability of the found
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* caps, or #NULL
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*
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* Tries to find what type of data is contained in the given @data, the
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* assumption being that the data 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 @data could not be identified.
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*
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* Free-function: gst_caps_unref
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*
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* Returns: (transfer full): the #GstCaps corresponding to the data, or #NULL
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* if no type could be found. The caller should free the caps returned
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* with gst_caps_unref().
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*/
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GstCaps *
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gst_type_find_helper_for_data (GstObject * obj, const guint8 * data, gsize size,
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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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GstCaps *result = NULL;
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g_return_val_if_fail (data != NULL, NULL);
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helper.data = data;
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helper.size = size;
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helper.best_probability = GST_TYPE_FIND_NONE;
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helper.caps = NULL;
|
|
helper.obj = obj;
|
|
|
|
if (helper.data == NULL || helper.size == 0)
|
|
return NULL;
|
|
|
|
find.data = &helper;
|
|
find.peek = buf_helper_find_peek;
|
|
find.suggest = buf_helper_find_suggest;
|
|
find.get_length = NULL;
|
|
|
|
type_list = gst_type_find_factory_get_list ();
|
|
|
|
for (l = type_list; l; l = l->next) {
|
|
helper.factory = GST_TYPE_FIND_FACTORY (l->data);
|
|
gst_type_find_factory_call_function (helper.factory, &find);
|
|
if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)
|
|
break;
|
|
}
|
|
gst_plugin_feature_list_free (type_list);
|
|
|
|
if (helper.best_probability > 0)
|
|
result = helper.caps;
|
|
|
|
if (prob)
|
|
*prob = helper.best_probability;
|
|
|
|
GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",
|
|
result, (guint) helper.best_probability);
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* gst_type_find_helper_for_buffer:
|
|
* @obj: object doing the typefinding, or NULL (used for logging)
|
|
* @buf: (in) (transfer none): a #GstBuffer with data to typefind
|
|
* @prob: (out) (allow-none): location to store the probability of the found
|
|
* caps, or #NULL
|
|
*
|
|
* Tries to find what type of data is contained in the given #GstBuffer, the
|
|
* assumption being that the buffer represents the beginning of the stream or
|
|
* file.
|
|
*
|
|
* All available typefinders will be called on the data in order of rank. If
|
|
* a typefinding function returns a probability of #GST_TYPE_FIND_MAXIMUM,
|
|
* typefinding is stopped immediately and the found caps will be returned
|
|
* right away. Otherwise, all available typefind functions will the tried,
|
|
* and the caps with the highest probability will be returned, or #NULL if
|
|
* the content of the buffer could not be identified.
|
|
*
|
|
* Free-function: gst_caps_unref
|
|
*
|
|
* Returns: (transfer full): the #GstCaps corresponding to the data, or #NULL
|
|
* if no type could be found. The caller should free the caps returned
|
|
* with gst_caps_unref().
|
|
*/
|
|
GstCaps *
|
|
gst_type_find_helper_for_buffer (GstObject * obj, GstBuffer * buf,
|
|
GstTypeFindProbability * prob)
|
|
{
|
|
GstCaps *result;
|
|
GstMapInfo info;
|
|
|
|
g_return_val_if_fail (buf != NULL, NULL);
|
|
g_return_val_if_fail (GST_IS_BUFFER (buf), NULL);
|
|
g_return_val_if_fail (GST_BUFFER_OFFSET (buf) == 0 ||
|
|
GST_BUFFER_OFFSET (buf) == GST_BUFFER_OFFSET_NONE, NULL);
|
|
|
|
if (!gst_buffer_map (buf, &info, GST_MAP_READ))
|
|
return NULL;
|
|
result = gst_type_find_helper_for_data (obj, info.data, info.size, prob);
|
|
gst_buffer_unmap (buf, &info);
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* gst_type_find_helper_for_extension:
|
|
* @obj: (allow-none): object doing the typefinding, or NULL (used for logging)
|
|
* @extension: an extension
|
|
*
|
|
* Tries to find the best #GstCaps associated with @extension.
|
|
*
|
|
* All available typefinders will be checked against the extension in order
|
|
* of rank. The caps of the first typefinder that can handle @extension will be
|
|
* returned.
|
|
*
|
|
* Free-function: gst_caps_unref
|
|
*
|
|
* Returns: (transfer full): the #GstCaps corresponding to @extension, or
|
|
* #NULL if no type could be found. The caller should free the caps
|
|
* returned with gst_caps_unref().
|
|
*
|
|
* Since: 0.10.23
|
|
*/
|
|
GstCaps *
|
|
gst_type_find_helper_for_extension (GstObject * obj, const gchar * extension)
|
|
{
|
|
GList *l, *type_list;
|
|
GstCaps *result = NULL;
|
|
|
|
g_return_val_if_fail (extension != NULL, NULL);
|
|
|
|
GST_LOG_OBJECT (obj, "finding caps for extension %s", extension);
|
|
|
|
type_list = gst_type_find_factory_get_list ();
|
|
|
|
for (l = type_list; l; l = g_list_next (l)) {
|
|
GstTypeFindFactory *factory;
|
|
gchar **ext;
|
|
gint i;
|
|
|
|
factory = GST_TYPE_FIND_FACTORY (l->data);
|
|
|
|
/* we only want to check those factories without a function */
|
|
if (factory->function != NULL)
|
|
continue;
|
|
|
|
/* get the extension that this typefind factory can handle */
|
|
ext = gst_type_find_factory_get_extensions (factory);
|
|
if (ext == NULL)
|
|
continue;
|
|
|
|
/* there are extension, see if one of them matches the requested
|
|
* extension */
|
|
for (i = 0; ext[i]; i++) {
|
|
if (strcmp (ext[i], extension) == 0) {
|
|
/* we found a matching extension, take the caps */
|
|
if ((result = gst_type_find_factory_get_caps (factory))) {
|
|
gst_caps_ref (result);
|
|
goto done;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
done:
|
|
gst_plugin_feature_list_free (type_list);
|
|
|
|
GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT, result);
|
|
|
|
return result;
|
|
}
|