gstreamer/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c
Edward Hervey 34a1245905 subparsers: Give proper category to subtitle "decoders"
Some subtitle "decoders" had a wrong category of "Parser", which `parsebin`
relies on to identify elements which do not *decode* streams but *parse* them.

This would cause such subtitle decoders to be plugged in within parsebin,
preventing the original stream to be properly used by (more efficient)
downstream decoders or subtitle renderers.

Fixes #1757

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6153>
2024-02-22 14:39:54 +00:00

432 lines
12 KiB
C

/* GStreamer SSA subtitle parser
* Copyright (c) 2006 Tim-Philipp Müller <tim centricular net>
*
* 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.
*/
/* Super-primitive SSA parser - we just want the text and ignore
* everything else like styles and timing codes etc. for now */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <ctype.h> /* isspace() */
#include <stdio.h> /* sscanf() */
#include <stdlib.h> /* atoi() */
#include <string.h>
#include "gstssaparse.h"
#include "gstsubparseelements.h"
GST_DEBUG_CATEGORY_STATIC (ssa_parse_debug);
#undef GST_CAT_DEFAULT
#define GST_CAT_DEFAULT ssa_parse_debug
static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-ssa; application/x-ass")
);
static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("text/x-raw, format=pango-markup")
);
#define gst_ssa_parse_parent_class parent_class
G_DEFINE_TYPE (GstSsaParse, gst_ssa_parse, GST_TYPE_ELEMENT);
GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (ssaparse, "ssaparse",
GST_RANK_PRIMARY, GST_TYPE_SSA_PARSE, sub_parse_element_init (plugin));
static GstStateChangeReturn gst_ssa_parse_change_state (GstElement *
element, GstStateChange transition);
static gboolean gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps);
static gboolean gst_ssa_parse_src_event (GstPad * pad, GstObject * parent,
GstEvent * event);
static gboolean gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent,
GstEvent * event);
static GstFlowReturn gst_ssa_parse_chain (GstPad * sinkpad, GstObject * parent,
GstBuffer * buf);
static void
gst_ssa_parse_dispose (GObject * object)
{
GstSsaParse *parse = GST_SSA_PARSE (object);
g_free (parse->ini);
parse->ini = NULL;
GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
}
static void
gst_ssa_parse_init (GstSsaParse * parse)
{
parse->sinkpad = gst_pad_new_from_static_template (&sink_templ, "sink");
gst_pad_set_chain_function (parse->sinkpad,
GST_DEBUG_FUNCPTR (gst_ssa_parse_chain));
gst_pad_set_event_function (parse->sinkpad,
GST_DEBUG_FUNCPTR (gst_ssa_parse_sink_event));
gst_element_add_pad (GST_ELEMENT (parse), parse->sinkpad);
parse->srcpad = gst_pad_new_from_static_template (&src_templ, "src");
gst_pad_set_event_function (parse->srcpad,
GST_DEBUG_FUNCPTR (gst_ssa_parse_src_event));
gst_element_add_pad (GST_ELEMENT (parse), parse->srcpad);
gst_pad_use_fixed_caps (parse->srcpad);
parse->ini = NULL;
parse->framed = FALSE;
parse->send_tags = FALSE;
}
static void
gst_ssa_parse_class_init (GstSsaParseClass * klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
object_class->dispose = gst_ssa_parse_dispose;
gst_element_class_add_static_pad_template (element_class, &sink_templ);
gst_element_class_add_static_pad_template (element_class, &src_templ);
gst_element_class_set_static_metadata (element_class,
"SSA Subtitle Parser", "Codec/Decoder/Subtitle",
"Parses SSA subtitle streams",
"Tim-Philipp Müller <tim centricular net>");
GST_DEBUG_CATEGORY_INIT (ssa_parse_debug, "ssaparse", 0,
"SSA subtitle parser");
element_class->change_state = GST_DEBUG_FUNCPTR (gst_ssa_parse_change_state);
}
static gboolean
gst_ssa_parse_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
return gst_pad_event_default (pad, parent, event);
}
static gboolean
gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
gboolean res;
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_CAPS:
{
GstCaps *caps;
gst_event_parse_caps (event, &caps);
res = gst_ssa_parse_setcaps (pad, caps);
gst_event_unref (event);
break;
}
default:
res = gst_pad_event_default (pad, parent, event);
break;
}
return res;
}
static gboolean
gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps)
{
GstSsaParse *parse = GST_SSA_PARSE (GST_PAD_PARENT (sinkpad));
GstCaps *outcaps;
const GValue *val;
GstStructure *s;
const guchar bom_utf8[] = { 0xEF, 0xBB, 0xBF };
const gchar *end;
GstBuffer *priv;
GstMapInfo map;
gchar *ptr;
gsize left, bad_offset;
gboolean ret;
s = gst_caps_get_structure (caps, 0);
val = gst_structure_get_value (s, "codec_data");
if (val == NULL) {
parse->framed = FALSE;
GST_ERROR ("Only SSA subtitles embedded in containers are supported");
return FALSE;
}
parse->framed = TRUE;
parse->send_tags = TRUE;
priv = (GstBuffer *) g_value_get_boxed (val);
g_return_val_if_fail (priv != NULL, FALSE);
gst_buffer_ref (priv);
if (!gst_buffer_map (priv, &map, GST_MAP_READ)) {
gst_buffer_unref (priv);
return FALSE;
}
GST_MEMDUMP_OBJECT (parse, "init section", map.data, map.size);
ptr = (gchar *) map.data;
left = map.size;
/* skip UTF-8 BOM */
if (left >= 3 && memcmp (ptr, bom_utf8, 3) == 0) {
ptr += 3;
left -= 3;
}
if (!strstr (ptr, "[Script Info]"))
goto invalid_init;
if (!g_utf8_validate (ptr, left, &end)) {
bad_offset = (gsize) (end - ptr);
GST_WARNING_OBJECT (parse, "Init section is not valid UTF-8. Problem at "
"byte offset %" G_GSIZE_FORMAT, bad_offset);
/* continue with valid UTF-8 data */
left = bad_offset;
}
/* FIXME: parse initial section */
if (parse->ini)
g_free (parse->ini);
parse->ini = g_strndup (ptr, left);
GST_LOG_OBJECT (parse, "Init section:\n%s", parse->ini);
gst_buffer_unmap (priv, &map);
gst_buffer_unref (priv);
outcaps = gst_caps_new_simple ("text/x-raw",
"format", G_TYPE_STRING, "pango-markup", NULL);
ret = gst_pad_set_caps (parse->srcpad, outcaps);
gst_caps_unref (outcaps);
return ret;
/* ERRORS */
invalid_init:
{
GST_WARNING_OBJECT (parse, "Invalid Init section - no Script Info header");
gst_buffer_unmap (priv, &map);
gst_buffer_unref (priv);
return FALSE;
}
}
static gboolean
gst_ssa_parse_remove_override_codes (GstSsaParse * parse, gchar * txt)
{
gchar *t, *end;
gboolean removed_any = FALSE;
while ((t = strchr (txt, '{'))) {
end = strchr (txt, '}');
if (end == NULL) {
GST_WARNING_OBJECT (parse, "Missing { for style override code");
return removed_any;
}
/* move terminating NUL character forward as well */
memmove (t, end + 1, strlen (end + 1) + 1);
removed_any = TRUE;
}
/* these may occur outside of curly brackets. We don't handle the different
* wrapping modes yet, so just remove these markers from the text for now */
while ((t = strstr (txt, "\\n"))) {
t[0] = ' ';
t[1] = '\n';
}
while ((t = strstr (txt, "\\N"))) {
t[0] = ' ';
t[1] = '\n';
}
while ((t = strstr (txt, "\\h"))) {
t[0] = ' ';
t[1] = ' ';
}
return removed_any;
}
/**
* gst_ssa_parse_push_line:
* @parse: caller element
* @txt: text to push
* @start: timestamp for the buffer
* @duration: duration for the buffer
*
* Parse the text in a buffer with the given properties and
* push it to the srcpad of the @parse element
*
* Returns: result of the push of the created buffer
*/
static GstFlowReturn
gst_ssa_parse_push_line (GstSsaParse * parse, gchar * txt,
GstClockTime start, GstClockTime duration)
{
GstFlowReturn ret;
GstBuffer *buf;
gchar *t, *escaped;
gint num, i, len;
num = atoi (txt);
GST_LOG_OBJECT (parse, "Parsing line #%d at %" GST_TIME_FORMAT,
num, GST_TIME_ARGS (start));
/* skip all non-text fields before the actual text */
t = txt;
for (i = 0; i < 8; ++i) {
t = strchr (t, ',');
if (t == NULL)
return GST_FLOW_ERROR;
++t;
}
GST_LOG_OBJECT (parse, "Text : %s", t);
if (gst_ssa_parse_remove_override_codes (parse, t)) {
GST_LOG_OBJECT (parse, "Clean: %s", t);
}
/* we claim to output pango markup, so we must escape the
* text even if we don't actually use any pango markup yet */
escaped = g_markup_printf_escaped ("%s", t);
len = strlen (escaped);
/* allocate enough for a terminating NUL, but don't include it in buf size */
buf = gst_buffer_new_and_alloc (len + 1);
gst_buffer_fill (buf, 0, escaped, len + 1);
gst_buffer_set_size (buf, len);
g_free (escaped);
GST_BUFFER_TIMESTAMP (buf) = start;
GST_BUFFER_DURATION (buf) = duration;
GST_LOG_OBJECT (parse, "Pushing buffer with timestamp %" GST_TIME_FORMAT
" and duration %" GST_TIME_FORMAT, GST_TIME_ARGS (start),
GST_TIME_ARGS (duration));
ret = gst_pad_push (parse->srcpad, buf);
if (ret != GST_FLOW_OK) {
GST_DEBUG_OBJECT (parse, "Push of text '%s' returned flow %s", txt,
gst_flow_get_name (ret));
}
return ret;
}
static GstFlowReturn
gst_ssa_parse_chain (GstPad * sinkpad, GstObject * parent, GstBuffer * buf)
{
GstFlowReturn ret;
GstSsaParse *parse = GST_SSA_PARSE (parent);
GstClockTime ts;
gchar *txt;
GstMapInfo map;
if (G_UNLIKELY (!parse->framed))
goto not_framed;
if (G_UNLIKELY (parse->send_tags)) {
GstTagList *tags;
tags = gst_tag_list_new_empty ();
gst_tag_list_add (tags, GST_TAG_MERGE_APPEND, GST_TAG_SUBTITLE_CODEC,
"SubStation Alpha", NULL);
gst_pad_push_event (parse->srcpad, gst_event_new_tag (tags));
parse->send_tags = FALSE;
}
/* make double-sure it's 0-terminated and all */
gst_buffer_map (buf, &map, GST_MAP_READ);
txt = g_strndup ((gchar *) map.data, map.size);
gst_buffer_unmap (buf, &map);
if (txt == NULL)
goto empty_text;
ts = GST_BUFFER_TIMESTAMP (buf);
ret = gst_ssa_parse_push_line (parse, txt, ts, GST_BUFFER_DURATION (buf));
if (ret != GST_FLOW_OK && GST_CLOCK_TIME_IS_VALID (ts)) {
GstSegment segment;
/* just advance time without sending anything */
gst_segment_init (&segment, GST_FORMAT_TIME);
segment.start = ts;
segment.time = ts;
gst_pad_push_event (parse->srcpad, gst_event_new_segment (&segment));
ret = GST_FLOW_OK;
}
gst_buffer_unref (buf);
g_free (txt);
return ret;
/* ERRORS */
not_framed:
{
GST_ELEMENT_ERROR (parse, STREAM, FORMAT, (NULL),
("Only SSA subtitles embedded in containers are supported"));
gst_buffer_unref (buf);
return GST_FLOW_NOT_NEGOTIATED;
}
empty_text:
{
GST_ELEMENT_WARNING (parse, STREAM, FORMAT, (NULL),
("Received empty subtitle"));
gst_buffer_unref (buf);
return GST_FLOW_OK;
}
}
static GstStateChangeReturn
gst_ssa_parse_change_state (GstElement * element, GstStateChange transition)
{
GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
GstSsaParse *parse = GST_SSA_PARSE (element);
switch (transition) {
case GST_STATE_CHANGE_READY_TO_PAUSED:
break;
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
if (ret == GST_STATE_CHANGE_FAILURE)
return ret;
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_READY:
g_free (parse->ini);
parse->ini = NULL;
parse->framed = FALSE;
break;
default:
break;
}
return ret;
}