1 /* GStreamer H.263 Parser
2  * Copyright (C) <2010> Arun Raghavan <arun.raghavan@collabora.co.uk>
3  * Copyright (C) <2010> Edward Hervey <edward.hervey@collabora.co.uk>
4  * Copyright (C) <2010> Collabora Multimedia
5  * Copyright (C) <2010> Nokia Corporation
6  *
7  * Some bits C-c,C-v'ed and s/4/3 from h264parse:
8  *           (C) 2005 Michal Benes <michal.benes@itonis.tv>
9  *           (C) 2008 Wim Taymans <wim.taymans@gmail.com>
10  *           (C) 2009 Mark Nauwelaerts <mnauw users sf net>
11  *
12  * This library is free software; you can redistribute it and/or
13  * modify it under the terms of the GNU Library General Public
14  * License as published by the Free Software Foundation; either
15  * version 2 of the License, or (at your option) any later version.
16  *
17  * This library is distributed in the hope that it will be useful,
18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20  * Library General Public License for more details.
21  *
22  * You should have received a copy of the GNU Library General Public
23  * License along with this library; if not, write to the
24  * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
25  * Boston, MA 02110-1301, USA.
26  */
27 
28 #ifdef HAVE_CONFIG_H
29 #  include "config.h"
30 #endif
31 
32 #include <gst/base/base.h>
33 #include <gst/pbutils/pbutils.h>
34 #include "gsth263parse.h"
35 
36 #include <string.h>
37 
38 GST_DEBUG_CATEGORY (h263_parse_debug);
39 #define GST_CAT_DEFAULT h263_parse_debug
40 
41 static GstStaticPadTemplate srctemplate =
42 GST_STATIC_PAD_TEMPLATE ("src", GST_PAD_SRC,
43     GST_PAD_ALWAYS,
44     GST_STATIC_CAPS ("video/x-h263, variant = (string) itu, "
45         "parsed = (boolean) true, framerate=(fraction)[0/1,MAX]")
46     );
47 
48 static GstStaticPadTemplate sinktemplate =
49 GST_STATIC_PAD_TEMPLATE ("sink", GST_PAD_SINK,
50     GST_PAD_ALWAYS,
51     GST_STATIC_CAPS ("video/x-h263, variant = (string) itu")
52     );
53 
54 #define parent_class gst_h263_parse_parent_class
55 G_DEFINE_TYPE (GstH263Parse, gst_h263_parse, GST_TYPE_BASE_PARSE);
56 
57 static gboolean gst_h263_parse_start (GstBaseParse * parse);
58 static gboolean gst_h263_parse_stop (GstBaseParse * parse);
59 static gboolean gst_h263_parse_sink_event (GstBaseParse * parse,
60     GstEvent * event);
61 static GstFlowReturn gst_h263_parse_handle_frame (GstBaseParse * parse,
62     GstBaseParseFrame * frame, gint * skipsize);
63 static GstFlowReturn gst_h263_parse_pre_push_frame (GstBaseParse * parse,
64     GstBaseParseFrame * frame);
65 static GstCaps *gst_h263_parse_get_sink_caps (GstBaseParse * parse,
66     GstCaps * filter);
67 
68 static void
gst_h263_parse_class_init(GstH263ParseClass * klass)69 gst_h263_parse_class_init (GstH263ParseClass * klass)
70 {
71   GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
72   GstBaseParseClass *parse_class = GST_BASE_PARSE_CLASS (klass);
73 
74   GST_DEBUG_CATEGORY_INIT (h263_parse_debug, "h263parse", 0, "h263 parser");
75 
76   gst_element_class_add_static_pad_template (gstelement_class, &srctemplate);
77   gst_element_class_add_static_pad_template (gstelement_class, &sinktemplate);
78   gst_element_class_set_static_metadata (gstelement_class, "H.263 parser",
79       "Codec/Parser/Video",
80       "Parses H.263 streams",
81       "Arun Raghavan <arun.raghavan@collabora.co.uk>,"
82       "Edward Hervey <edward.hervey@collabora.co.uk>");
83 
84   /* Override BaseParse vfuncs */
85   parse_class->start = GST_DEBUG_FUNCPTR (gst_h263_parse_start);
86   parse_class->stop = GST_DEBUG_FUNCPTR (gst_h263_parse_stop);
87   parse_class->sink_event = GST_DEBUG_FUNCPTR (gst_h263_parse_sink_event);
88   parse_class->handle_frame = GST_DEBUG_FUNCPTR (gst_h263_parse_handle_frame);
89   parse_class->pre_push_frame =
90       GST_DEBUG_FUNCPTR (gst_h263_parse_pre_push_frame);
91   parse_class->get_sink_caps = GST_DEBUG_FUNCPTR (gst_h263_parse_get_sink_caps);
92 }
93 
94 static void
gst_h263_parse_init(GstH263Parse * h263parse)95 gst_h263_parse_init (GstH263Parse * h263parse)
96 {
97   GST_PAD_SET_ACCEPT_INTERSECT (GST_BASE_PARSE_SINK_PAD (h263parse));
98   GST_PAD_SET_ACCEPT_TEMPLATE (GST_BASE_PARSE_SINK_PAD (h263parse));
99 }
100 
101 static gboolean
gst_h263_parse_start(GstBaseParse * parse)102 gst_h263_parse_start (GstBaseParse * parse)
103 {
104   GstH263Parse *h263parse = GST_H263_PARSE (parse);
105 
106   GST_DEBUG_OBJECT (h263parse, "start");
107 
108   h263parse->bitrate = 0;
109   h263parse->profile = -1;
110   h263parse->level = -1;
111 
112   h263parse->state = PARSING;
113 
114   h263parse->sent_codec_tag = FALSE;
115 
116   gst_base_parse_set_min_frame_size (parse, 4);
117 
118   return TRUE;
119 }
120 
121 static gboolean
gst_h263_parse_stop(GstBaseParse * parse)122 gst_h263_parse_stop (GstBaseParse * parse)
123 {
124   GST_DEBUG_OBJECT (parse, "stop");
125 
126   return TRUE;
127 }
128 
129 static gboolean
gst_h263_parse_sink_event(GstBaseParse * parse,GstEvent * event)130 gst_h263_parse_sink_event (GstBaseParse * parse, GstEvent * event)
131 {
132   GstH263Parse *h263parse;
133 
134   h263parse = GST_H263_PARSE (parse);
135 
136   switch (GST_EVENT_TYPE (event)) {
137     case GST_EVENT_TAG:
138     {
139       GstTagList *taglist;
140 
141       gst_event_parse_tag (event, &taglist);
142 
143       if (gst_tag_list_get_uint (taglist, GST_TAG_BITRATE, &h263parse->bitrate))
144         GST_DEBUG_OBJECT (h263parse, "got bitrate tag: %u", h263parse->bitrate);
145 
146       break;
147     }
148     default:
149       break;
150   }
151 
152   return GST_BASE_PARSE_CLASS (parent_class)->sink_event (parse, event);
153 }
154 
155 static guint
find_psc(GstBuffer * buffer,guint skip)156 find_psc (GstBuffer * buffer, guint skip)
157 {
158   GstMapInfo map;
159   GstByteReader br;
160   guint psc_pos = -1, psc;
161 
162   gst_buffer_map (buffer, &map, GST_MAP_READ);
163   gst_byte_reader_init (&br, map.data, map.size);
164 
165   if (!gst_byte_reader_set_pos (&br, skip))
166     goto out;
167 
168   if (gst_byte_reader_peek_uint24_be (&br, &psc) == FALSE)
169     goto out;
170 
171   /* Scan for the picture start code (22 bits - 0x0020)
172    * startcode  : 0000 0000 0000 0000 1000 00xx
173    * mask (bin) : 1111 1111 1111 1111 1111 1100
174    * mask (hex) :    f    f    f    f    f    c
175    * match      :    0    0    0    0    8    0
176    */
177   while ((gst_byte_reader_get_remaining (&br) >= 3)) {
178     if (gst_byte_reader_peek_uint24_be (&br, &psc) &&
179         ((psc & 0xfffffc) == 0x000080)) {
180       psc_pos = gst_byte_reader_get_pos (&br);
181       break;
182     } else if (gst_byte_reader_skip (&br, 1) == FALSE)
183       break;
184   }
185 
186 out:
187   gst_buffer_unmap (buffer, &map);
188   return psc_pos;
189 }
190 
191 static void
gst_h263_parse_set_src_caps(GstH263Parse * h263parse,const H263Params * params)192 gst_h263_parse_set_src_caps (GstH263Parse * h263parse,
193     const H263Params * params)
194 {
195   GstStructure *st = NULL;
196   GstCaps *caps, *sink_caps;
197   gint fr_num, fr_denom, par_num, par_denom;
198 
199   g_assert (h263parse->state == PASSTHROUGH || h263parse->state == GOT_HEADER);
200 
201   caps = gst_pad_get_current_caps (GST_BASE_PARSE_SINK_PAD (h263parse));
202   if (caps) {
203     caps = gst_caps_make_writable (caps);
204   } else {
205     caps = gst_caps_new_simple ("video/x-h263",
206         "variant", G_TYPE_STRING, "itu", NULL);
207   }
208   gst_caps_set_simple (caps, "parsed", G_TYPE_BOOLEAN, TRUE, NULL);
209 
210   sink_caps = gst_pad_get_current_caps (GST_BASE_PARSE_SINK_PAD (h263parse));
211   if (sink_caps && (st = gst_caps_get_structure (sink_caps, 0)) &&
212       gst_structure_get_fraction (st, "framerate", &fr_num, &fr_denom)) {
213     /* Got it in caps - nothing more to do */
214     GST_DEBUG_OBJECT (h263parse, "sink caps override framerate from headers");
215   } else {
216     /* Caps didn't have the framerate - get it from params */
217     gst_h263_parse_get_framerate (params, &fr_num, &fr_denom);
218   }
219   gst_caps_set_simple (caps, "framerate", GST_TYPE_FRACTION, fr_num, fr_denom,
220       NULL);
221 
222   if (params->width && params->height)
223     gst_caps_set_simple (caps, "width", G_TYPE_INT, params->width,
224         "height", G_TYPE_INT, params->height, NULL);
225 
226   if (st != NULL
227       && gst_structure_get_fraction (st, "pixel-aspect-ratio", &par_num,
228           &par_denom)) {
229     /* Got it in caps - nothing more to do */
230     GST_DEBUG_OBJECT (h263parse, "sink caps override PAR");
231   } else {
232     /* Caps didn't have the framerate - get it from params */
233     gst_h263_parse_get_par (params, &par_num, &par_denom);
234   }
235   gst_caps_set_simple (caps, "pixel-aspect-ratio", GST_TYPE_FRACTION,
236       par_num, par_denom, NULL);
237 
238   if (h263parse->state == GOT_HEADER) {
239     gst_caps_set_simple (caps,
240         "annex-d", G_TYPE_BOOLEAN, (params->features & H263_OPTION_UMV_MODE),
241         "annex-e", G_TYPE_BOOLEAN, (params->features & H263_OPTION_SAC_MODE),
242         "annex-f", G_TYPE_BOOLEAN, (params->features & H263_OPTION_AP_MODE),
243         "annex-g", G_TYPE_BOOLEAN, (params->features & H263_OPTION_PB_MODE),
244         "annex-i", G_TYPE_BOOLEAN, (params->features & H263_OPTION_AIC_MODE),
245         "annex-j", G_TYPE_BOOLEAN, (params->features & H263_OPTION_DF_MODE),
246         "annex-k", G_TYPE_BOOLEAN, (params->features & H263_OPTION_SS_MODE),
247         "annex-m", G_TYPE_BOOLEAN, (params->type == PICTURE_IMPROVED_PB),
248         "annex-n", G_TYPE_BOOLEAN, (params->features & H263_OPTION_RPS_MODE),
249         "annex-q", G_TYPE_BOOLEAN, (params->features & H263_OPTION_RRU_MODE),
250         "annex-r", G_TYPE_BOOLEAN, (params->features & H263_OPTION_ISD_MODE),
251         "annex-s", G_TYPE_BOOLEAN, (params->features & H263_OPTION_AIV_MODE),
252         "annex-t", G_TYPE_BOOLEAN, (params->features & H263_OPTION_MQ_MODE),
253         "annex-u", G_TYPE_BOOLEAN, (params->features & H263_OPTION_ERPS_MODE),
254         "annex-v", G_TYPE_BOOLEAN, (params->features & H263_OPTION_DPS_MODE),
255         NULL);
256 
257     h263parse->profile = gst_h263_parse_get_profile (params);
258     if (h263parse->profile != -1) {
259       gchar *profile_str;
260 
261       profile_str = g_strdup_printf ("%u", h263parse->profile);
262       gst_caps_set_simple (caps, "profile", G_TYPE_STRING, profile_str, NULL);
263       g_free (profile_str);
264     }
265 
266     h263parse->level = gst_h263_parse_get_level (params, h263parse->profile,
267         h263parse->bitrate, fr_num, fr_denom);
268     if (h263parse->level != -1) {
269       gchar *level_str;
270 
271       level_str = g_strdup_printf ("%u", h263parse->level);
272       gst_caps_set_simple (caps, "level", G_TYPE_STRING, level_str, NULL);
273       g_free (level_str);
274     }
275   }
276 
277   gst_pad_set_caps (GST_BASE_PARSE_SRC_PAD (GST_BASE_PARSE (h263parse)), caps);
278   gst_caps_unref (caps);
279   if (sink_caps)
280     gst_caps_unref (sink_caps);
281 }
282 
283 static GstFlowReturn
gst_h263_parse_handle_frame(GstBaseParse * parse,GstBaseParseFrame * frame,gint * skipsize)284 gst_h263_parse_handle_frame (GstBaseParse * parse,
285     GstBaseParseFrame * frame, gint * skipsize)
286 {
287   GstH263Parse *h263parse;
288   GstBuffer *buffer;
289   guint psc_pos, next_psc_pos;
290   gsize size;
291   H263Params params = { 0, };
292   GstFlowReturn res = GST_FLOW_OK;
293 
294   h263parse = GST_H263_PARSE (parse);
295   buffer = frame->buffer;
296   size = gst_buffer_get_size (buffer);
297 
298   if (size < 3) {
299     *skipsize = 1;
300     return GST_FLOW_OK;
301   }
302 
303   psc_pos = find_psc (buffer, 0);
304 
305   if (psc_pos == -1) {
306     /* PSC not found, need more data */
307     if (size > 3)
308       psc_pos = size - 3;
309     else
310       psc_pos = 0;
311     goto more;
312   }
313 
314   /* need to skip */
315   if (psc_pos > 0)
316     goto more;
317 
318   /* Found the start of the frame, now try to find the end */
319   next_psc_pos = psc_pos + 3;
320   next_psc_pos = find_psc (buffer, next_psc_pos);
321 
322   if (next_psc_pos == -1) {
323     if (GST_BASE_PARSE_DRAINING (parse))
324       /* FLUSH/EOS, it's okay if we can't find the next frame */
325       next_psc_pos = size;
326     else
327       goto more;
328   }
329 
330   /* We should now have a complete frame */
331 
332   /* If this is the first frame, parse and set srcpad caps */
333   if (h263parse->state == PARSING) {
334     res = gst_h263_parse_get_params (&params, buffer, FALSE, &h263parse->state);
335     if (res != GST_FLOW_OK || h263parse->state != GOT_HEADER) {
336       GST_WARNING ("Couldn't parse header - setting passthrough mode");
337       gst_base_parse_set_passthrough (parse, TRUE);
338     } else {
339       /* Set srcpad caps since we now have sufficient information to do so */
340       gst_h263_parse_set_src_caps (h263parse, &params);
341       gst_base_parse_set_passthrough (parse, FALSE);
342     }
343     memset (&params, 0, sizeof (params));
344   }
345 
346   /* XXX: After getting a keyframe, should we adjust min_frame_size to
347    * something smaller so we don't end up collecting too many non-keyframes? */
348 
349   GST_DEBUG_OBJECT (h263parse, "found a frame of size %u at pos %u",
350       next_psc_pos, psc_pos);
351 
352   res = gst_h263_parse_get_params (&params, buffer, TRUE, &h263parse->state);
353   if (res != GST_FLOW_OK)
354     goto more;
355 
356   if (h263parse->state == PASSTHROUGH || h263parse->state == PARSING) {
357     /* There's a feature we don't support, or we didn't have enough data to
358      * parse the header, which should not be possible. Either way, go into
359      * passthrough mode and let downstream handle it if it can. */
360     GST_WARNING ("Couldn't parse header - setting passthrough mode");
361     gst_base_parse_set_passthrough (parse, TRUE);
362     goto more;
363   }
364 
365   if (gst_h263_parse_is_delta_unit (&params))
366     GST_BUFFER_FLAG_UNSET (buffer, GST_BUFFER_FLAG_DELTA_UNIT);
367   else
368     GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_DELTA_UNIT);
369 
370   return gst_base_parse_finish_frame (parse, frame, next_psc_pos);
371 
372 more:
373   *skipsize = psc_pos;
374 
375   return res;
376 }
377 
378 static void
remove_fields(GstCaps * caps)379 remove_fields (GstCaps * caps)
380 {
381   guint i, n;
382 
383   n = gst_caps_get_size (caps);
384   for (i = 0; i < n; i++) {
385     GstStructure *s = gst_caps_get_structure (caps, i);
386 
387     gst_structure_remove_field (s, "parsed");
388   }
389 }
390 
391 static GstCaps *
gst_h263_parse_get_sink_caps(GstBaseParse * parse,GstCaps * filter)392 gst_h263_parse_get_sink_caps (GstBaseParse * parse, GstCaps * filter)
393 {
394   GstCaps *peercaps, *templ;
395   GstCaps *res;
396 
397   templ = gst_pad_get_pad_template_caps (GST_BASE_PARSE_SINK_PAD (parse));
398   if (filter) {
399     GstCaps *fcopy = gst_caps_copy (filter);
400     /* Remove the fields we convert */
401     remove_fields (fcopy);
402     peercaps = gst_pad_peer_query_caps (GST_BASE_PARSE_SRC_PAD (parse), fcopy);
403     gst_caps_unref (fcopy);
404   } else
405     peercaps = gst_pad_peer_query_caps (GST_BASE_PARSE_SRC_PAD (parse), NULL);
406 
407   if (peercaps) {
408     /* Remove parsed field */
409     peercaps = gst_caps_make_writable (peercaps);
410     remove_fields (peercaps);
411 
412     res = gst_caps_intersect_full (peercaps, templ, GST_CAPS_INTERSECT_FIRST);
413     gst_caps_unref (peercaps);
414     gst_caps_unref (templ);
415   } else {
416     res = templ;
417   }
418 
419   if (filter) {
420     GstCaps *intersection;
421 
422     intersection =
423         gst_caps_intersect_full (filter, res, GST_CAPS_INTERSECT_FIRST);
424     gst_caps_unref (res);
425     res = intersection;
426   }
427 
428   return res;
429 }
430 
431 static GstFlowReturn
gst_h263_parse_pre_push_frame(GstBaseParse * parse,GstBaseParseFrame * frame)432 gst_h263_parse_pre_push_frame (GstBaseParse * parse, GstBaseParseFrame * frame)
433 {
434   GstH263Parse *h263parse = GST_H263_PARSE (parse);
435 
436   if (!h263parse->sent_codec_tag) {
437     GstTagList *taglist;
438     GstCaps *caps;
439 
440     /* codec tag */
441     caps = gst_pad_get_current_caps (GST_BASE_PARSE_SRC_PAD (parse));
442     if (G_UNLIKELY (caps == NULL)) {
443       if (GST_PAD_IS_FLUSHING (GST_BASE_PARSE_SRC_PAD (parse))) {
444         GST_INFO_OBJECT (parse, "Src pad is flushing");
445         return GST_FLOW_FLUSHING;
446       } else {
447         GST_INFO_OBJECT (parse, "Src pad is not negotiated!");
448         return GST_FLOW_NOT_NEGOTIATED;
449       }
450     }
451 
452     taglist = gst_tag_list_new_empty ();
453     gst_pb_utils_add_codec_description_to_tag_list (taglist,
454         GST_TAG_VIDEO_CODEC, caps);
455     gst_caps_unref (caps);
456 
457     gst_base_parse_merge_tags (parse, taglist, GST_TAG_MERGE_REPLACE);
458     gst_tag_list_unref (taglist);
459 
460     /* also signals the end of first-frame processing */
461     h263parse->sent_codec_tag = TRUE;
462   }
463 
464   return GST_FLOW_OK;
465 }
466