| /* GStreamer |
| * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu> |
| * Copyright (C) 2000,2005 Wim Taymans <wim@fluendo.com> |
| * Copyright (C) 2006 Tim-Philipp Müller <tim centricular net> |
| * |
| * gsttypefindhelper.c: |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Library General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public |
| * License along with this library; if not, write to the |
| * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| */ |
| |
| /** |
| * SECTION:gsttypefindhelper |
| * @short_description: Utility functions for typefinding |
| * |
| * Utility functions for elements doing typefinding: |
| * gst_type_find_helper() does typefinding in pull mode, while |
| * gst_type_find_helper_for_buffer() is useful for elements needing to do |
| * typefinding in push mode from a chain function. |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| # include "config.h" |
| #endif |
| |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include "gsttypefindhelper.h" |
| |
| /* ********************** typefinding in pull mode ************************ */ |
| |
| static void |
| helper_find_suggest (gpointer data, GstTypeFindProbability probability, |
| GstCaps * caps); |
| |
| typedef struct |
| { |
| GstBuffer *buffer; |
| GstMapInfo map; |
| } GstMappedBuffer; |
| |
| typedef struct |
| { |
| GSList *buffers; /* buffer cache */ |
| guint64 size; |
| guint64 last_offset; |
| GstTypeFindHelperGetRangeFunction func; |
| GstTypeFindProbability best_probability; |
| GstCaps *caps; |
| GstTypeFindFactory *factory; /* for logging */ |
| GstObject *obj; /* for logging */ |
| GstObject *parent; |
| } GstTypeFindHelper; |
| |
| /* |
| * helper_find_peek: |
| * @data: helper data struct |
| * @off: stream offset |
| * @size: block size |
| * |
| * Get data pointer within a stream. Keeps a cache of read buffers (partly |
| * for performance reasons, but mostly because pointers returned by us need |
| * to stay valid until typefinding has finished) |
| * |
| * Returns: (nullable): address of the data or %NULL if buffer does not cover |
| * the requested range. |
| */ |
| static const guint8 * |
| helper_find_peek (gpointer data, gint64 offset, guint size) |
| { |
| GstTypeFindHelper *helper; |
| GstBuffer *buffer; |
| GstFlowReturn ret; |
| GSList *insert_pos = NULL; |
| gsize buf_size; |
| guint64 buf_offset; |
| GstMappedBuffer *bmap; |
| #if 0 |
| GstCaps *caps; |
| #endif |
| |
| helper = (GstTypeFindHelper *) data; |
| |
| GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT |
| ", %u)", GST_OBJECT_NAME (helper->factory), offset, size); |
| |
| if (size == 0) |
| return NULL; |
| |
| if (offset < 0) { |
| if (helper->size == -1 || helper->size < -offset) |
| return NULL; |
| |
| offset += helper->size; |
| } |
| |
| /* see if we have a matching buffer already in our list */ |
| if (size > 0 && offset <= helper->last_offset) { |
| GSList *walk; |
| |
| for (walk = helper->buffers; walk; walk = walk->next) { |
| GstMappedBuffer *bmp = (GstMappedBuffer *) walk->data; |
| GstBuffer *buf = GST_BUFFER_CAST (bmp->buffer); |
| |
| buf_offset = GST_BUFFER_OFFSET (buf); |
| buf_size = bmp->map.size; |
| |
| /* buffers are kept sorted by end offset (highest first) in the list, so |
| * at this point we save the current position and stop searching if |
| * we're after the searched end offset */ |
| if (buf_offset <= offset) { |
| if ((offset + size) < (buf_offset + buf_size)) { |
| /* must already have been mapped before */ |
| return (guint8 *) bmp->map.data + (offset - buf_offset); |
| } |
| } else if (offset + size >= buf_offset + buf_size) { |
| insert_pos = walk; |
| break; |
| } |
| } |
| } |
| |
| buffer = NULL; |
| /* some typefinders go in 1 byte steps over 1k of data and request |
| * small buffers. It is really inefficient to pull each time, and pulling |
| * a larger chunk is almost free. Trying to pull a larger chunk at the end |
| * of the file is also not a problem here, we'll just get a truncated buffer |
| * in that case (and we'll have to double-check the size we actually get |
| * anyway, see below) */ |
| ret = |
| helper->func (helper->obj, helper->parent, offset, MAX (size, 4096), |
| &buffer); |
| |
| if (ret != GST_FLOW_OK) |
| goto error; |
| |
| #if 0 |
| caps = GST_BUFFER_CAPS (buffer); |
| |
| if (caps && !gst_caps_is_empty (caps) && !gst_caps_is_any (caps)) { |
| GST_DEBUG ("buffer has caps %" GST_PTR_FORMAT ", suggest max probability", |
| caps); |
| |
| gst_caps_replace (&helper->caps, caps); |
| helper->best_probability = GST_TYPE_FIND_MAXIMUM; |
| |
| gst_buffer_unref (buffer); |
| return NULL; |
| } |
| #endif |
| |
| /* getrange might silently return shortened buffers at the end of a file, |
| * we must, however, always return either the full requested data or %NULL */ |
| buf_offset = GST_BUFFER_OFFSET (buffer); |
| buf_size = gst_buffer_get_size (buffer); |
| |
| if ((buf_offset != -1 && buf_offset != offset) || buf_size < size) { |
| GST_DEBUG ("dropping short buffer: %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT |
| " instead of %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT, |
| buf_offset, buf_offset + buf_size - 1, offset, offset + size - 1); |
| gst_buffer_unref (buffer); |
| return NULL; |
| } |
| |
| bmap = g_slice_new0 (GstMappedBuffer); |
| |
| if (!gst_buffer_map (buffer, &bmap->map, GST_MAP_READ)) |
| goto map_failed; |
| |
| bmap->buffer = buffer; |
| |
| if (insert_pos) { |
| helper->buffers = g_slist_insert_before (helper->buffers, insert_pos, bmap); |
| } else { |
| /* if insert_pos is not set, our offset is bigger than the largest offset |
| * we have so far; since we keep the list sorted with highest offsets |
| * first, we need to prepend the buffer to the list */ |
| helper->last_offset = GST_BUFFER_OFFSET (buffer) + buf_size; |
| helper->buffers = g_slist_prepend (helper->buffers, bmap); |
| } |
| |
| return bmap->map.data; |
| |
| error: |
| { |
| GST_INFO ("typefind function returned: %s", gst_flow_get_name (ret)); |
| return NULL; |
| } |
| map_failed: |
| { |
| GST_ERROR ("map failed"); |
| gst_buffer_unref (buffer); |
| g_slice_free (GstMappedBuffer, bmap); |
| return NULL; |
| } |
| } |
| |
| /* |
| * helper_find_suggest: |
| * @data: helper data struct |
| * @probability: probability of the match |
| * @caps: caps of the type |
| * |
| * If given @probability is higher, replace previously store caps. |
| */ |
| static void |
| helper_find_suggest (gpointer data, GstTypeFindProbability probability, |
| GstCaps * caps) |
| { |
| GstTypeFindHelper *helper = (GstTypeFindHelper *) data; |
| |
| GST_LOG_OBJECT (helper->obj, |
| "'%s' called suggest (%u, %" GST_PTR_FORMAT ")", |
| GST_OBJECT_NAME (helper->factory), probability, caps); |
| |
| if (probability > helper->best_probability) { |
| gst_caps_replace (&helper->caps, caps); |
| helper->best_probability = probability; |
| } |
| } |
| |
| static guint64 |
| helper_find_get_length (gpointer data) |
| { |
| GstTypeFindHelper *helper = (GstTypeFindHelper *) data; |
| |
| GST_LOG_OBJECT (helper->obj, "'%s' called get_length, returning %" |
| G_GUINT64_FORMAT, GST_OBJECT_NAME (helper->factory), helper->size); |
| |
| return helper->size; |
| } |
| |
| /** |
| * gst_type_find_helper_get_range: |
| * @obj: A #GstObject that will be passed as first argument to @func |
| * @parent: (allow-none): the parent of @obj or %NULL |
| * @func: (scope call): A generic #GstTypeFindHelperGetRangeFunction that will |
| * be used to access data at random offsets when doing the typefinding |
| * @size: The length in bytes |
| * @extension: extension of the media |
| * @prob: (out) (allow-none): location to store the probability of the found |
| * caps, or %NULL |
| * |
| * Utility function to do pull-based typefinding. Unlike gst_type_find_helper() |
| * however, this function will use the specified function @func to obtain the |
| * data needed by the typefind functions, rather than operating on a given |
| * source pad. This is useful mostly for elements like tag demuxers which |
| * strip off data at the beginning and/or end of a file and want to typefind |
| * the stripped data stream before adding their own source pad (the specified |
| * callback can then call the upstream peer pad with offsets adjusted for the |
| * tag size, for example). |
| * |
| * When @extension is not %NULL, this function will first try the typefind |
| * functions for the given extension, which might speed up the typefinding |
| * in many cases. |
| * |
| * Free-function: gst_caps_unref |
| * |
| * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data |
| * stream. Returns %NULL if no #GstCaps matches the data stream. |
| */ |
| GstCaps * |
| gst_type_find_helper_get_range (GstObject * obj, GstObject * parent, |
| GstTypeFindHelperGetRangeFunction func, guint64 size, |
| const gchar * extension, GstTypeFindProbability * prob) |
| { |
| GstTypeFindHelper helper; |
| GstTypeFind find; |
| GSList *walk; |
| GList *l, *type_list; |
| GstCaps *result = NULL; |
| gint pos = 0; |
| |
| g_return_val_if_fail (GST_IS_OBJECT (obj), NULL); |
| g_return_val_if_fail (func != NULL, NULL); |
| |
| helper.buffers = NULL; |
| helper.size = size; |
| helper.last_offset = 0; |
| helper.func = func; |
| helper.best_probability = GST_TYPE_FIND_NONE; |
| helper.caps = NULL; |
| helper.obj = obj; |
| helper.parent = parent; |
| |
| find.data = &helper; |
| find.peek = helper_find_peek; |
| find.suggest = helper_find_suggest; |
| |
| if (size == 0 || size == (guint64) - 1) { |
| find.get_length = NULL; |
| } else { |
| find.get_length = helper_find_get_length; |
| } |
| |
| type_list = gst_type_find_factory_get_list (); |
| |
| /* move the typefinders for the extension first in the list. The idea is that |
| * when one of them returns MAX we don't need to search further as there is a |
| * very high chance we got the right type. */ |
| if (extension) { |
| GList *next; |
| |
| GST_LOG_OBJECT (obj, "sorting typefind for extension %s to head", |
| extension); |
| |
| for (l = type_list; l; l = next) { |
| const gchar *const *ext; |
| GstTypeFindFactory *factory; |
| |
| next = l->next; |
| |
| factory = GST_TYPE_FIND_FACTORY (l->data); |
| |
| ext = gst_type_find_factory_get_extensions (factory); |
| if (ext == NULL) |
| continue; |
| |
| GST_LOG_OBJECT (obj, "testing factory %s for extension %s", |
| GST_OBJECT_NAME (factory), extension); |
| |
| while (*ext != NULL) { |
| if (strcmp (*ext, extension) == 0) { |
| /* found extension, move in front */ |
| GST_LOG_OBJECT (obj, "moving typefind for extension %s to head", |
| extension); |
| /* remove entry from list */ |
| type_list = g_list_delete_link (type_list, l); |
| /* insert at the position */ |
| type_list = g_list_insert (type_list, factory, pos); |
| /* next element will be inserted after this one */ |
| pos++; |
| break; |
| } |
| ++ext; |
| } |
| } |
| } |
| |
| 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); |
| |
| for (walk = helper.buffers; walk; walk = walk->next) { |
| GstMappedBuffer *bmap = (GstMappedBuffer *) walk->data; |
| |
| gst_buffer_unmap (bmap->buffer, &bmap->map); |
| gst_buffer_unref (bmap->buffer); |
| g_slice_free (GstMappedBuffer, bmap); |
| } |
| g_slist_free (helper.buffers); |
| |
| 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: |
| * @src: A source #GstPad |
| * @size: The length in bytes |
| * |
| * Tries to find what type of data is flowing from the given source #GstPad. |
| * |
| * Free-function: gst_caps_unref |
| * |
| * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data |
| * stream. Returns %NULL if no #GstCaps matches the data stream. |
| */ |
| |
| GstCaps * |
| gst_type_find_helper (GstPad * src, guint64 size) |
| { |
| GstTypeFindHelperGetRangeFunction func; |
| |
| g_return_val_if_fail (GST_IS_OBJECT (src), NULL); |
| g_return_val_if_fail (GST_PAD_GETRANGEFUNC (src) != NULL, NULL); |
| |
| func = (GstTypeFindHelperGetRangeFunction) (GST_PAD_GETRANGEFUNC (src)); |
| |
| return gst_type_find_helper_get_range (GST_OBJECT (src), |
| GST_OBJECT_PARENT (src), func, size, NULL, NULL); |
| } |
| |
| /* ********************** typefinding for buffers ************************* */ |
| |
| typedef struct |
| { |
| const guint8 *data; /* buffer data */ |
| gsize size; |
| GstTypeFindProbability best_probability; |
| GstCaps *caps; |
| GstTypeFindFactory *factory; /* for logging */ |
| GstObject *obj; /* for logging */ |
| } GstTypeFindBufHelper; |
| |
| /* |
| * buf_helper_find_peek: |
| * @data: helper data struct |
| * @off: stream offset |
| * @size: block size |
| * |
| * Get data pointer within a buffer. |
| * |
| * Returns: (nullable): address inside the buffer or %NULL if buffer does not |
| * cover the requested range. |
| */ |
| static const guint8 * |
| buf_helper_find_peek (gpointer data, gint64 off, guint size) |
| { |
| GstTypeFindBufHelper *helper; |
| |
| helper = (GstTypeFindBufHelper *) data; |
| GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT ", %u)", |
| GST_OBJECT_NAME (helper->factory), off, size); |
| |
| if (size == 0) |
| return NULL; |
| |
| if (off < 0) { |
| GST_LOG_OBJECT (helper->obj, "'%s' wanted to peek at end; not supported", |
| GST_OBJECT_NAME (helper->factory)); |
| return NULL; |
| } |
| |
| if ((off + size) <= helper->size) |
| return helper->data + off; |
| |
| return NULL; |
| } |
| |
| /* |
| * buf_helper_find_suggest: |
| * @data: helper data struct |
| * @probability: probability of the match |
| * @caps: caps of the type |
| * |
| * If given @probability is higher, replace previously store caps. |
| */ |
| static void |
| buf_helper_find_suggest (gpointer data, GstTypeFindProbability probability, |
| GstCaps * caps) |
| { |
| GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data; |
| |
| GST_LOG_OBJECT (helper->obj, |
| "'%s' called suggest (%u, %" GST_PTR_FORMAT ")", |
| GST_OBJECT_NAME (helper->factory), probability, caps); |
| |
| /* Note: not >= as we call typefinders in order of rank, highest first */ |
| if (probability > helper->best_probability) { |
| gst_caps_replace (&helper->caps, caps); |
| helper->best_probability = probability; |
| } |
| } |
| |
| /** |
| * gst_type_find_helper_for_data: |
| * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging) |
| * @data: (in) (transfer none): a pointer with data to typefind |
| * @size: (in) (transfer none): the size of @data |
| * @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 @data, the |
| * assumption being that the data 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 @data could not be identified. |
| * |
| * Free-function: gst_caps_unref |
| * |
| * Returns: (transfer full) (nullable): 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_data (GstObject * obj, const guint8 * data, gsize size, |
| GstTypeFindProbability * prob) |
| { |
| GstTypeFindBufHelper helper; |
| GstTypeFind find; |
| GList *l, *type_list; |
| GstCaps *result = NULL; |
| |
| g_return_val_if_fail (data != NULL, NULL); |
| |
| helper.data = data; |
| helper.size = size; |
| helper.best_probability = GST_TYPE_FIND_NONE; |
| 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: (allow-none): 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) (nullable): 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) (nullable): the #GstCaps corresponding to |
| * @extension, 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_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; |
| const gchar *const *ext; |
| |
| factory = GST_TYPE_FIND_FACTORY (l->data); |
| |
| /* we only want to check those factories without a function */ |
| if (gst_type_find_factory_has_function (factory)) |
| 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 */ |
| while (*ext != NULL) { |
| if (strcmp (*ext, 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; |
| } |
| } |
| ++ext; |
| } |
| } |
| done: |
| gst_plugin_feature_list_free (type_list); |
| |
| GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT, result); |
| |
| return result; |
| } |