/* GStreamer * Copyright (C) <1999> Erik Walthinsen * * 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., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ /** * SECTION:element-jpegenc * * Encodes jpeg images. * * * Example launch line * |[ * gst-launch videotestsrc num-buffers=50 ! video/x-raw-yuv, framerate='(fraction)'5/1 ! jpegenc ! avimux ! filesink location=mjpeg.avi * ]| a pipeline to mux 5 JPEG frames per second into a 10 sec. long motion jpeg * avi. * */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include "gstjpegenc.h" #include "gstjpeg.h" #include /* experimental */ /* setting smoothig seems to have no effect in libjepeg #define ENABLE_SMOOTHING 1 */ GST_DEBUG_CATEGORY_STATIC (jpegenc_debug); #define GST_CAT_DEFAULT jpegenc_debug #define JPEG_DEFAULT_QUALITY 85 #define JPEG_DEFAULT_SMOOTHING 0 #define JPEG_DEFAULT_IDCT_METHOD JDCT_FASTEST /* JpegEnc signals and args */ enum { /* FILL ME */ LAST_SIGNAL }; enum { PROP_0, PROP_QUALITY, PROP_SMOOTHING, PROP_IDCT_METHOD }; static void gst_jpegenc_reset (GstJpegEnc * enc); static void gst_jpegenc_finalize (GObject * object); static GstFlowReturn gst_jpegenc_chain (GstPad * pad, GstObject * parent, GstBuffer * buf); static gboolean gst_jpegenc_sink_event (GstPad * pad, GstObject * parent, GstEvent * event); static GstCaps *gst_jpegenc_getcaps (GstPad * pad, GstCaps * filter); static gboolean gst_jpegenc_sink_query (GstPad * pad, GstObject * parent, GstQuery * query); static void gst_jpegenc_resync (GstJpegEnc * jpegenc); static void gst_jpegenc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec); static void gst_jpegenc_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec); static GstStateChangeReturn gst_jpegenc_change_state (GstElement * element, GstStateChange transition); #define gst_jpegenc_parent_class parent_class G_DEFINE_TYPE (GstJpegEnc, gst_jpegenc, GST_TYPE_ELEMENT); /* *INDENT-OFF* */ static GstStaticPadTemplate gst_jpegenc_sink_pad_template = GST_STATIC_PAD_TEMPLATE ("sink", GST_PAD_SINK, GST_PAD_ALWAYS, GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("{ I420, YV12, YUY2, UYVY, Y41B, Y42B, YVYU, Y444, " "RGB, BGR, RGBx, xRGB, BGRx, xBGR, GRAY8 }")) ); /* *INDENT-ON* */ static GstStaticPadTemplate gst_jpegenc_src_pad_template = GST_STATIC_PAD_TEMPLATE ("src", GST_PAD_SRC, GST_PAD_ALWAYS, GST_STATIC_CAPS ("image/jpeg, " "width = (int) [ 16, 65535 ], " "height = (int) [ 16, 65535 ], " "framerate = (fraction) [ 0/1, MAX ]") ); static void gst_jpegenc_class_init (GstJpegEncClass * klass) { GObjectClass *gobject_class; GstElementClass *gstelement_class; gobject_class = (GObjectClass *) klass; gstelement_class = (GstElementClass *) klass; gobject_class->finalize = gst_jpegenc_finalize; gobject_class->set_property = gst_jpegenc_set_property; gobject_class->get_property = gst_jpegenc_get_property; g_object_class_install_property (gobject_class, PROP_QUALITY, g_param_spec_int ("quality", "Quality", "Quality of encoding", 0, 100, JPEG_DEFAULT_QUALITY, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); #ifdef ENABLE_SMOOTHING /* disabled, since it doesn't seem to work */ g_object_class_install_property (gobject_class, PROP_SMOOTHING, g_param_spec_int ("smoothing", "Smoothing", "Smoothing factor", 0, 100, JPEG_DEFAULT_SMOOTHING, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); #endif g_object_class_install_property (gobject_class, PROP_IDCT_METHOD, g_param_spec_enum ("idct-method", "IDCT Method", "The IDCT algorithm to use", GST_TYPE_IDCT_METHOD, JPEG_DEFAULT_IDCT_METHOD, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); gstelement_class->change_state = gst_jpegenc_change_state; gst_element_class_add_pad_template (gstelement_class, gst_static_pad_template_get (&gst_jpegenc_sink_pad_template)); gst_element_class_add_pad_template (gstelement_class, gst_static_pad_template_get (&gst_jpegenc_src_pad_template)); gst_element_class_set_details_simple (gstelement_class, "JPEG image encoder", "Codec/Encoder/Image", "Encode images in JPEG format", "Wim Taymans "); GST_DEBUG_CATEGORY_INIT (jpegenc_debug, "jpegenc", 0, "JPEG encoding element"); } static void ensure_memory (GstJpegEnc * jpegenc) { GstMemory *new_memory; GstMapInfo map; gsize old_size, desired_size, new_size; guint8 *new_data; static GstAllocationParams params = { 0, 0, 0, 3, }; old_size = jpegenc->output_map.size; if (old_size == 0) desired_size = jpegenc->bufsize; else desired_size = old_size * 2; /* Our output memory wasn't big enough. * Make a new memory that's twice the size, */ new_memory = gst_allocator_alloc (NULL, desired_size, ¶ms); gst_memory_map (new_memory, &map, GST_MAP_READWRITE); new_data = map.data; new_size = map.size; /* copy previous data if any */ if (jpegenc->output_mem) { memcpy (new_data, jpegenc->output_map.data, old_size); gst_memory_unmap (jpegenc->output_mem, &jpegenc->output_map); gst_memory_unref (jpegenc->output_mem); } /* drop it into place, */ jpegenc->output_mem = new_memory; jpegenc->output_map = map; /* and last, update libjpeg on where to work. */ jpegenc->jdest.next_output_byte = new_data + old_size; jpegenc->jdest.free_in_buffer = new_size - old_size; } static void gst_jpegenc_init_destination (j_compress_ptr cinfo) { GST_DEBUG ("gst_jpegenc_chain: init_destination"); } static boolean gst_jpegenc_flush_destination (j_compress_ptr cinfo) { GstJpegEnc *jpegenc = (GstJpegEnc *) (cinfo->client_data); GST_DEBUG_OBJECT (jpegenc, "gst_jpegenc_chain: flush_destination: buffer too small"); ensure_memory (jpegenc); return TRUE; } static void gst_jpegenc_term_destination (j_compress_ptr cinfo) { GstJpegEnc *jpegenc = (GstJpegEnc *) (cinfo->client_data); GST_DEBUG_OBJECT (jpegenc, "gst_jpegenc_chain: term_source"); gst_memory_unmap (jpegenc->output_mem, &jpegenc->output_map); /* Trim the buffer size. we will push it in the chain function */ gst_memory_resize (jpegenc->output_mem, 0, jpegenc->output_map.size - jpegenc->jdest.free_in_buffer); jpegenc->output_map.data = NULL; jpegenc->output_map.size = 0; } static void gst_jpegenc_init (GstJpegEnc * jpegenc) { /* create the sink and src pads */ jpegenc->sinkpad = gst_pad_new_from_static_template (&gst_jpegenc_sink_pad_template, "sink"); gst_pad_set_chain_function (jpegenc->sinkpad, GST_DEBUG_FUNCPTR (gst_jpegenc_chain)); gst_pad_set_query_function (jpegenc->sinkpad, GST_DEBUG_FUNCPTR (gst_jpegenc_sink_query)); gst_pad_set_event_function (jpegenc->sinkpad, GST_DEBUG_FUNCPTR (gst_jpegenc_sink_event)); gst_element_add_pad (GST_ELEMENT (jpegenc), jpegenc->sinkpad); jpegenc->srcpad = gst_pad_new_from_static_template (&gst_jpegenc_src_pad_template, "src"); gst_pad_use_fixed_caps (jpegenc->srcpad); gst_element_add_pad (GST_ELEMENT (jpegenc), jpegenc->srcpad); /* reset the initial video state */ gst_video_info_init (&jpegenc->info); /* setup jpeglib */ memset (&jpegenc->cinfo, 0, sizeof (jpegenc->cinfo)); memset (&jpegenc->jerr, 0, sizeof (jpegenc->jerr)); jpegenc->cinfo.err = jpeg_std_error (&jpegenc->jerr); jpeg_create_compress (&jpegenc->cinfo); jpegenc->jdest.init_destination = gst_jpegenc_init_destination; jpegenc->jdest.empty_output_buffer = gst_jpegenc_flush_destination; jpegenc->jdest.term_destination = gst_jpegenc_term_destination; jpegenc->cinfo.dest = &jpegenc->jdest; jpegenc->cinfo.client_data = jpegenc; /* init properties */ jpegenc->quality = JPEG_DEFAULT_QUALITY; jpegenc->smoothing = JPEG_DEFAULT_SMOOTHING; jpegenc->idct_method = JPEG_DEFAULT_IDCT_METHOD; gst_jpegenc_reset (jpegenc); } static void gst_jpegenc_reset (GstJpegEnc * enc) { gint i, j; g_free (enc->line[0]); g_free (enc->line[1]); g_free (enc->line[2]); enc->line[0] = NULL; enc->line[1] = NULL; enc->line[2] = NULL; for (i = 0; i < 3; i++) { for (j = 0; j < 4 * DCTSIZE; j++) { g_free (enc->row[i][j]); enc->row[i][j] = NULL; } } gst_video_info_init (&enc->info); } static void gst_jpegenc_finalize (GObject * object) { GstJpegEnc *filter = GST_JPEGENC (object); jpeg_destroy_compress (&filter->cinfo); G_OBJECT_CLASS (parent_class)->finalize (object); } static GstCaps * gst_jpegenc_getcaps (GstPad * pad, GstCaps * filter) { GstJpegEnc *jpegenc = GST_JPEGENC (gst_pad_get_parent (pad)); GstCaps *caps, *othercaps; GstCaps *templ; gint i, j; GstStructure *structure = NULL; /* we want to proxy properties like width, height and framerate from the other end of the element */ othercaps = gst_pad_peer_query_caps (jpegenc->srcpad, filter); templ = gst_pad_get_pad_template_caps (pad); if (othercaps == NULL || gst_caps_is_empty (othercaps) || gst_caps_is_any (othercaps)) { caps = templ; goto done; } caps = gst_caps_new_empty (); for (i = 0; i < gst_caps_get_size (templ); i++) { /* pick fields from peer caps */ for (j = 0; j < gst_caps_get_size (othercaps); j++) { GstStructure *s = gst_caps_get_structure (othercaps, j); const GValue *val; structure = gst_structure_copy (gst_caps_get_structure (templ, i)); if ((val = gst_structure_get_value (s, "width"))) gst_structure_set_value (structure, "width", val); if ((val = gst_structure_get_value (s, "height"))) gst_structure_set_value (structure, "height", val); if ((val = gst_structure_get_value (s, "framerate"))) gst_structure_set_value (structure, "framerate", val); caps = gst_caps_merge_structure (caps, structure); } } gst_caps_unref (templ); done: gst_caps_replace (&othercaps, NULL); gst_object_unref (jpegenc); return caps; } static gboolean gst_jpegenc_sink_query (GstPad * pad, GstObject * parent, GstQuery * query) { gboolean res; switch (GST_QUERY_TYPE (query)) { case GST_QUERY_CAPS: { GstCaps *filter, *caps; gst_query_parse_caps (query, &filter); caps = gst_jpegenc_getcaps (pad, filter); gst_query_set_caps_result (query, caps); gst_caps_unref (caps); res = TRUE; break; } default: res = gst_pad_query_default (pad, parent, query); break; } return res; } static gboolean gst_jpegenc_setcaps (GstJpegEnc * enc, GstCaps * caps) { GstVideoInfo info; gint i; GstCaps *othercaps; gboolean ret; const GstVideoFormatInfo *vinfo; /* get info from caps */ if (!gst_video_info_from_caps (&info, caps)) goto refuse_caps; /* store input description */ enc->info = info; vinfo = info.finfo; /* prepare a cached image description */ enc->channels = 3 + (GST_VIDEO_FORMAT_INFO_HAS_ALPHA (vinfo) ? 1 : 0); /* ... but any alpha is disregarded in encoding */ if (GST_VIDEO_FORMAT_INFO_IS_GRAY (vinfo)) enc->channels = 1; else enc->channels = 3; enc->h_max_samp = 0; enc->v_max_samp = 0; for (i = 0; i < enc->channels; ++i) { enc->cwidth[i] = GST_VIDEO_INFO_COMP_WIDTH (&info, i); enc->cheight[i] = GST_VIDEO_INFO_COMP_HEIGHT (&info, i); enc->inc[i] = GST_VIDEO_INFO_COMP_PSTRIDE (&info, i); enc->h_samp[i] = GST_ROUND_UP_4 (info.width) / enc->cwidth[i]; enc->h_max_samp = MAX (enc->h_max_samp, enc->h_samp[i]); enc->v_samp[i] = GST_ROUND_UP_4 (info.height) / enc->cheight[i]; enc->v_max_samp = MAX (enc->v_max_samp, enc->v_samp[i]); } /* samp should only be 1, 2 or 4 */ g_assert (enc->h_max_samp <= 4); g_assert (enc->v_max_samp <= 4); /* now invert */ /* maximum is invariant, as one of the components should have samp 1 */ for (i = 0; i < enc->channels; ++i) { enc->h_samp[i] = enc->h_max_samp / enc->h_samp[i]; enc->v_samp[i] = enc->v_max_samp / enc->v_samp[i]; } enc->planar = (enc->inc[0] == 1 && enc->inc[1] == 1 && enc->inc[2] == 1); othercaps = gst_caps_copy (gst_pad_get_pad_template_caps (enc->srcpad)); gst_caps_set_simple (othercaps, "width", G_TYPE_INT, info.width, "height", G_TYPE_INT, info.height, NULL); if (info.fps_d > 0) gst_caps_set_simple (othercaps, "framerate", GST_TYPE_FRACTION, info.fps_n, info.fps_d, NULL); if (info.par_d > 0) gst_caps_set_simple (othercaps, "pixel-aspect-ratio", GST_TYPE_FRACTION, info.par_n, info.par_d, NULL); ret = gst_pad_set_caps (enc->srcpad, othercaps); gst_caps_unref (othercaps); if (ret) gst_jpegenc_resync (enc); return ret; /* ERRORS */ refuse_caps: { GST_WARNING_OBJECT (enc, "refused caps %" GST_PTR_FORMAT, caps); return FALSE; } } static gboolean gst_jpegenc_sink_event (GstPad * pad, GstObject * parent, GstEvent * event) { gboolean res; GstJpegEnc *enc = GST_JPEGENC (parent); switch (GST_EVENT_TYPE (event)) { case GST_EVENT_CAPS: { GstCaps *caps; gst_event_parse_caps (event, &caps); res = gst_jpegenc_setcaps (enc, caps); gst_event_unref (event); break; } default: res = gst_pad_event_default (pad, parent, event); break; } return res; } static void gst_jpegenc_resync (GstJpegEnc * jpegenc) { gint width, height; gint i, j; const GstVideoFormatInfo *finfo; GST_DEBUG_OBJECT (jpegenc, "resync"); finfo = jpegenc->info.finfo; jpegenc->cinfo.image_width = width = GST_VIDEO_INFO_WIDTH (&jpegenc->info); jpegenc->cinfo.image_height = height = GST_VIDEO_INFO_HEIGHT (&jpegenc->info); jpegenc->cinfo.input_components = jpegenc->channels; GST_DEBUG_OBJECT (jpegenc, "width %d, height %d", width, height); GST_DEBUG_OBJECT (jpegenc, "format %d", GST_VIDEO_INFO_FORMAT (&jpegenc->info)); if (GST_VIDEO_FORMAT_INFO_IS_RGB (finfo)) { GST_DEBUG_OBJECT (jpegenc, "RGB"); jpegenc->cinfo.in_color_space = JCS_RGB; } else if (GST_VIDEO_FORMAT_INFO_IS_GRAY (finfo)) { GST_DEBUG_OBJECT (jpegenc, "gray"); jpegenc->cinfo.in_color_space = JCS_GRAYSCALE; } else { GST_DEBUG_OBJECT (jpegenc, "YUV"); jpegenc->cinfo.in_color_space = JCS_YCbCr; } /* input buffer size as max output */ jpegenc->bufsize = GST_VIDEO_INFO_SIZE (&jpegenc->info); jpeg_set_defaults (&jpegenc->cinfo); jpegenc->cinfo.raw_data_in = TRUE; /* duh, libjpeg maps RGB to YUV ... and don't expect some conversion */ if (jpegenc->cinfo.in_color_space == JCS_RGB) jpeg_set_colorspace (&jpegenc->cinfo, JCS_RGB); GST_DEBUG_OBJECT (jpegenc, "h_max_samp=%d, v_max_samp=%d", jpegenc->h_max_samp, jpegenc->v_max_samp); /* image dimension info */ for (i = 0; i < jpegenc->channels; i++) { GST_DEBUG_OBJECT (jpegenc, "comp %i: h_samp=%d, v_samp=%d", i, jpegenc->h_samp[i], jpegenc->v_samp[i]); jpegenc->cinfo.comp_info[i].h_samp_factor = jpegenc->h_samp[i]; jpegenc->cinfo.comp_info[i].v_samp_factor = jpegenc->v_samp[i]; g_free (jpegenc->line[i]); jpegenc->line[i] = g_new (guchar *, jpegenc->v_max_samp * DCTSIZE); if (!jpegenc->planar) { for (j = 0; j < jpegenc->v_max_samp * DCTSIZE; j++) { g_free (jpegenc->row[i][j]); jpegenc->row[i][j] = g_malloc (width); jpegenc->line[i][j] = jpegenc->row[i][j]; } } } /* guard against a potential error in gst_jpegenc_term_destination which occurs iff bufsize % 4 < free_space_remaining */ jpegenc->bufsize = GST_ROUND_UP_4 (jpegenc->bufsize); jpeg_suppress_tables (&jpegenc->cinfo, TRUE); GST_DEBUG_OBJECT (jpegenc, "resync done"); } static GstFlowReturn gst_jpegenc_chain (GstPad * pad, GstObject * parent, GstBuffer * buf) { GstFlowReturn ret; GstJpegEnc *jpegenc; guint height; guchar *base[3], *end[3]; guint stride[3]; gint i, j, k; GstBuffer *outbuf; GstVideoFrame frame; static GstAllocationParams params = { 0, 0, 0, 3, }; jpegenc = GST_JPEGENC (parent); if (G_UNLIKELY (GST_VIDEO_INFO_FORMAT (&jpegenc->info) == GST_VIDEO_FORMAT_UNKNOWN)) goto not_negotiated; if (!gst_video_frame_map (&frame, &jpegenc->info, buf, GST_MAP_READ)) goto invalid_frame; height = GST_VIDEO_FRAME_HEIGHT (&frame); GST_LOG_OBJECT (jpegenc, "got buffer of %lu bytes", gst_buffer_get_size (buf)); for (i = 0; i < jpegenc->channels; i++) { base[i] = GST_VIDEO_FRAME_COMP_DATA (&frame, i); stride[i] = GST_VIDEO_FRAME_COMP_STRIDE (&frame, i); end[i] = base[i] + GST_VIDEO_FRAME_COMP_HEIGHT (&frame, i) * stride[i]; } jpegenc->output_mem = gst_allocator_alloc (NULL, jpegenc->bufsize, ¶ms); gst_memory_map (jpegenc->output_mem, &jpegenc->output_map, GST_MAP_READWRITE); jpegenc->jdest.next_output_byte = jpegenc->output_map.data; jpegenc->jdest.free_in_buffer = jpegenc->output_map.size; /* prepare for raw input */ #if JPEG_LIB_VERSION >= 70 jpegenc->cinfo.do_fancy_downsampling = FALSE; #endif jpegenc->cinfo.smoothing_factor = jpegenc->smoothing; jpegenc->cinfo.dct_method = jpegenc->idct_method; jpeg_set_quality (&jpegenc->cinfo, jpegenc->quality, TRUE); jpeg_start_compress (&jpegenc->cinfo, TRUE); GST_LOG_OBJECT (jpegenc, "compressing"); if (jpegenc->planar) { for (i = 0; i < height; i += jpegenc->v_max_samp * DCTSIZE) { for (k = 0; k < jpegenc->channels; k++) { for (j = 0; j < jpegenc->v_samp[k] * DCTSIZE; j++) { jpegenc->line[k][j] = base[k]; if (base[k] + stride[k] < end[k]) base[k] += stride[k]; } } jpeg_write_raw_data (&jpegenc->cinfo, jpegenc->line, jpegenc->v_max_samp * DCTSIZE); } } else { for (i = 0; i < height; i += jpegenc->v_max_samp * DCTSIZE) { for (k = 0; k < jpegenc->channels; k++) { for (j = 0; j < jpegenc->v_samp[k] * DCTSIZE; j++) { guchar *src, *dst; gint l; /* ouch, copy line */ src = base[k]; dst = jpegenc->line[k][j]; for (l = jpegenc->cwidth[k]; l > 0; l--) { *dst = *src; src += jpegenc->inc[k]; dst++; } if (base[k] + stride[k] < end[k]) base[k] += stride[k]; } } jpeg_write_raw_data (&jpegenc->cinfo, jpegenc->line, jpegenc->v_max_samp * DCTSIZE); } } /* This will ensure that gst_jpegenc_term_destination is called */ jpeg_finish_compress (&jpegenc->cinfo); GST_LOG_OBJECT (jpegenc, "compressing done"); outbuf = gst_buffer_new (); gst_buffer_copy_into (outbuf, buf, GST_BUFFER_COPY_METADATA, 0, -1); gst_buffer_append_memory (outbuf, jpegenc->output_mem); jpegenc->output_mem = NULL; ret = gst_pad_push (jpegenc->srcpad, outbuf); gst_video_frame_unmap (&frame); gst_buffer_unref (buf); return ret; /* ERRORS */ not_negotiated: { GST_WARNING_OBJECT (jpegenc, "no input format set (no caps on buffer)"); gst_buffer_unref (buf); return GST_FLOW_NOT_NEGOTIATED; } invalid_frame: { GST_WARNING_OBJECT (jpegenc, "invalid frame received"); gst_buffer_unref (buf); return GST_FLOW_OK; } } static void gst_jpegenc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstJpegEnc *jpegenc = GST_JPEGENC (object); GST_OBJECT_LOCK (jpegenc); switch (prop_id) { case PROP_QUALITY: jpegenc->quality = g_value_get_int (value); break; #ifdef ENABLE_SMOOTHING case PROP_SMOOTHING: jpegenc->smoothing = g_value_get_int (value); break; #endif case PROP_IDCT_METHOD: jpegenc->idct_method = g_value_get_enum (value); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } GST_OBJECT_UNLOCK (jpegenc); } static void gst_jpegenc_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstJpegEnc *jpegenc = GST_JPEGENC (object); GST_OBJECT_LOCK (jpegenc); switch (prop_id) { case PROP_QUALITY: g_value_set_int (value, jpegenc->quality); break; #ifdef ENABLE_SMOOTHING case PROP_SMOOTHING: g_value_set_int (value, jpegenc->smoothing); break; #endif case PROP_IDCT_METHOD: g_value_set_enum (value, jpegenc->idct_method); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } GST_OBJECT_UNLOCK (jpegenc); } static GstStateChangeReturn gst_jpegenc_change_state (GstElement * element, GstStateChange transition) { GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS; GstJpegEnc *filter = GST_JPEGENC (element); switch (transition) { case GST_STATE_CHANGE_NULL_TO_READY: GST_DEBUG_OBJECT (element, "setting line buffers"); filter->line[0] = NULL; filter->line[1] = NULL; filter->line[2] = NULL; 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: gst_jpegenc_reset (filter); break; default: break; } return ret; }