Add a GStreamer-based decoder module

GStreamer is a cross-platform multimedia processing
framework for audio/video postprocess/capture/
encode/decode/render.

This module is intended for Audio/Video decoding using
the available GStreamer plugins present in the system.
Currently this module supports only video decoding
and can be extended to audio decoding as well.
ZeroCopy is currently not supported and must be added.

Codecs currently supported are h264, mpeg4, vp8, mpeg2,
flashvideo, wmv1/2/3, vc1.
Signed-off-by: Vikram Fugro <vikram.fugro@gmail.com>
Signed-off-by: Jean-Baptiste <jb@videolan.org>

NEWS

@@ -27,6 +27,7 @@ Decoder:
  * New jpeg image decoder
  * Add tx3g subtitles decoder
  * Add Media Foundation Transform decoder
+ * Add decoder module based on GStreamer. Currently supports only video decode.
 
 Encoder:
  * Support for MPEG-2 encoding using x262

configure.ac

@@ -2255,6 +2255,26 @@ PKG_CHECK_EXISTS([libavutil], [
 ])
 AC_MSG_RESULT([${avfork}])
 
+dnl
+dnl gstreamer stuff
+dnl
+AC_ARG_ENABLE(gst-decode,
+  [  --enable-gst-decode     GStreamer based decoding support (currently supports only video decoding) (default auto)])
+
+have_gst_decode="no"
+AS_IF([test "${enable_gst_decode}" != "no"], [
+  PKG_CHECK_MODULES([GST_APP], [gstreamer-app-1.0], [
+    PKG_CHECK_MODULES([GST_VIDEO], [gstreamer-video-1.0], [
+      have_gst_decode="yes"
+    ], [
+      AC_MSG_WARN([${GST_VIDEO_PKG_ERRORS}. GStreamer decoder module will not be built.])
+    ])
+  ], [
+    AC_MSG_WARN([${GST_APP_PKG_ERRORS}. GStreamer modules will not be built.])
+  ])
+])
+AM_CONDITIONAL([HAVE_GST_DECODE], [test "${have_gst_decode}" = "yes"])
+
 dnl
 dnl  avcodec decoder/encoder plugin
 dnl

modules/MODULES_LIST

@@ -151,6 +151,7 @@ $Id$
  * grain: Grain Video filter
  * grey_yuv: grayscale to others conversion module
  * growl: announce currently playing stream to growl
+ * gstdecode: GStreamer based decoder module.
  * h264: H264 decoder
  * headphone_channel_mixer:  headphone channel mixer with virtual spatialization effect
  * hevc: HEVC demuxer

modules/codec/Makefile.am

@@ -470,3 +470,10 @@ libquicktime_plugin_la_LDFLAGS = $(AM_LDFLAGS) -rpath '$(codecdir)'
 libquicktime_plugin_la_LIBADD = $(LIBM)
 EXTRA_LTLIBRARIES += libquicktime_plugin.la
 codec_LTLIBRARIES += $(LTLIBquicktime)
+
+libgstdecode_plugin_la_SOURCES = codec/gstdecode.c
+libgstdecode_plugin_la_CFLAGS = $(AM_CFLAGS) $(GST_VIDEO_CFLAGS) $(GST_APP_CFLAGS)
+libgstdecode_plugin_la_LIBADD = $(GST_VIDEO_LIBS) $(GST_APP_LIBS)
+if HAVE_GST_DECODE
+codec_LTLIBRARIES += libgstdecode_plugin.la
+endif

modules/codec/gstdecode.c

+/*****************************************************************************
+ * gstdecode.c: Decoder module making use of gstreamer
+ *****************************************************************************
+ * Copyright (C) 2014 VLC authors and VideoLAN
+ * $Id:
+ *
+ * Author: Vikram Fugro <vikram.fugro@gmail.com>
+ *
+ * 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 2.1 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
+ * Lesser 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 Street, Fifth Floor, Boston, MA  02110-1301 USA
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_plugin.h>
+#include <vlc_codec.h>
+
+#include <gst/gst.h>
+#include <gst/video/video.h>
+#include <gst/video/gstvideometa.h>
+#include <gst/app/gstappsrc.h>
+#include <gst/gstatomicqueue.h>
+
+struct decoder_sys_t
+{
+    GstElement *p_decoder;
+    GstElement *p_decode_src;
+    GstElement *p_decode_in;
+    GstElement *p_decode_out;
+
+    GstBus *p_bus;
+
+    GstVideoInfo vinfo;
+    GstAtomicQueue *p_que;
+    bool b_prerolled;
+    bool b_running;
+};
+
+typedef struct
+{
+    GstCaps *p_sinkcaps;
+    GstCaps *p_srccaps;
+} sink_src_caps_t;
+
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static int  OpenDecoder( vlc_object_t* );
+static void CloseDecoder( vlc_object_t* );
+static picture_t *DecodeBlock( decoder_t*, block_t** );
+
+#define MODULE_DESCRIPTION N_( "Uses GStreamer framework's plugins " \
+        "to decode the media codecs" )
+
+#define USEDECODEBIN_TEXT N_( "Use DecodeBin" )
+#define USEDECODEBIN_LONGTEXT N_( \
+    "DecodeBin is a container element, that can add and " \
+    "manage multiple elements. Apart from adding the decoders, " \
+    "decodebin also adds elementary stream parsers which can provide " \
+    "more info such as codec profile, level and other attributes, " \
+    "in the form of GstCaps (Stream Capabilities) to decoder." )
+
+vlc_module_begin( )
+    set_shortname( "GstDecode" )
+    add_shortcut( "gstdecode" )
+    set_category( CAT_INPUT )
+    set_subcategory( SUBCAT_INPUT_VCODEC )
+    /* decoder main module */
+    set_description( N_( "GStreamer Based Decoder" ) )
+    set_help( MODULE_DESCRIPTION )
+    set_capability( "decoder", 50 )
+    set_section( N_( "Decoding" ) , NULL )
+    set_callbacks( OpenDecoder, CloseDecoder )
+    add_bool( "use-decodebin", false, USEDECODEBIN_TEXT,
+        USEDECODEBIN_LONGTEXT, false )
+vlc_module_end( )
+
+/* gst_init( ) is not thread-safe, hence a thread-safe wrapper */
+static void vlc_gst_init( void )
+{
+    static vlc_mutex_t init_lock = VLC_STATIC_MUTEX;
+
+    vlc_mutex_lock( &init_lock );
+    gst_init( NULL, NULL );
+    vlc_mutex_unlock( &init_lock );
+}
+
+static GstStructure* vlc_to_gst_fmt( const es_format_t *p_fmt )
+{
+    const video_format_t *p_vfmt = &p_fmt->video;
+    GstStructure *p_str = NULL;
+
+    switch( p_fmt->i_codec ){
+    case VLC_CODEC_H264:
+        p_str = gst_structure_new_empty( "video/x-h264" );
+        gst_structure_set( p_str, "alignment", G_TYPE_STRING, "au", NULL );
+        break;
+    case VLC_CODEC_MP4V:
+        p_str = gst_structure_new_empty( "video/mpeg" );
+        gst_structure_set( p_str, "mpegversion", G_TYPE_INT, 4,
+                "systemstream", G_TYPE_BOOLEAN, FALSE, NULL );
+        break;
+    case VLC_CODEC_VP8:
+        p_str = gst_structure_new_empty( "video/x-vp8" );
+        break;
+    case VLC_CODEC_MPGV:
+        p_str = gst_structure_new_empty( "video/mpeg" );
+        gst_structure_set( p_str, "mpegversion", G_TYPE_INT, 2,
+                "systemstream", G_TYPE_BOOLEAN, FALSE, NULL );
+        break;
+    case VLC_CODEC_FLV1:
+        p_str = gst_structure_new_empty( "video/x-flash-video" );
+        gst_structure_set( p_str, "flvversion", G_TYPE_INT, 1, NULL );
+        break;
+    case VLC_CODEC_WMV1:
+        p_str = gst_structure_new_empty( "video/x-wmv" );
+        gst_structure_set( p_str, "wmvversion", G_TYPE_INT, 1,
+                "format", G_TYPE_STRING, "WMV1", NULL );
+        break;
+    case VLC_CODEC_WMV2:
+        p_str = gst_structure_new_empty( "video/x-wmv" );
+        gst_structure_set( p_str, "wmvversion", G_TYPE_INT, 2,
+                "format", G_TYPE_STRING, "WMV2", NULL );
+        break;
+    case VLC_CODEC_WMV3:
+        p_str = gst_structure_new_empty( "video/x-wmv" );
+        gst_structure_set( p_str, "wmvversion", G_TYPE_INT, 3,
+                "format", G_TYPE_STRING, "WMV3", NULL );
+        break;
+    case VLC_CODEC_VC1:
+        p_str = gst_structure_new_empty( "video/x-wmv" );
+        gst_structure_set( p_str, "wmvversion", G_TYPE_INT, 3,
+                "format", G_TYPE_STRING, "WVC1", NULL );
+        break;
+    default:
+        /* unsupported codec */
+        return NULL;
+    }
+
+    if( p_vfmt->i_width && p_vfmt->i_height )
+        gst_structure_set( p_str,
+                "width", G_TYPE_INT, p_vfmt->i_width,
+                "height", G_TYPE_INT, p_vfmt->i_height, NULL );
+
+    if( p_vfmt->i_frame_rate && p_vfmt->i_frame_rate_base )
+        gst_structure_set( p_str, "framerate", GST_TYPE_FRACTION,
+                p_vfmt->i_frame_rate,
+                p_vfmt->i_frame_rate_base, NULL );
+
+    if( p_vfmt->i_sar_num && p_vfmt->i_sar_den )
+        gst_structure_set( p_str, "pixel-aspect-ratio", GST_TYPE_FRACTION,
+                p_vfmt->i_sar_num,
+                p_vfmt->i_sar_den, NULL );
+
+    if( p_fmt->i_extra )
+    {
+        GstBuffer *p_buf;
+
+        p_buf = gst_buffer_new_wrapped_full( GST_MEMORY_FLAG_READONLY,
+                p_fmt->p_extra, p_fmt->i_extra, 0,
+                p_fmt->i_extra, NULL, NULL );
+        if( p_buf == NULL )
+        {
+            gst_structure_free( p_str );
+            return NULL;
+        }
+
+        gst_structure_set( p_str, "codec_data", GST_TYPE_BUFFER, p_buf, NULL );
+        gst_buffer_unref( p_buf );
+    }
+
+    return p_str;
+}
+
+/* Emitted by appsrc when serving a seek request.
+ * Seek over here is only used for flushing the buffers.
+ * Returns TRUE always, as the 'real' seek will be
+ * done by VLC framework */
+static gboolean seek_data_cb( GstAppSrc *p_src, guint64 l_offset,
+        gpointer p_data )
+{
+    VLC_UNUSED( p_src );
+    decoder_t *p_dec = p_data;
+    msg_Dbg( p_dec, "appsrc seeking to %"G_GUINT64_FORMAT, l_offset );
+    return TRUE;
+}
+
+/* Emitted by decodebin when there are no more
+ * outputs.This signal is not really necessary
+ * to be connected. It is connected here for sanity
+ * check only, just in-case something unexpected
+ * happens inside decodebin in finding the appropriate
+ * decoder, and it fails to emit PAD_ADDED signal */
+static void no_more_pads_cb( GstElement *p_ele, gpointer p_data )
+{
+    VLC_UNUSED( p_ele );
+    decoder_t *p_dec = p_data;
+    decoder_sys_t *p_sys = p_dec->p_sys;
+    GstPad *p_pad;
+
+    msg_Dbg( p_dec, "no more pads" );
+
+    p_pad = gst_element_get_static_pad( p_sys->p_decode_out,
+            "sink" );
+    if( !gst_pad_is_linked( p_pad ) )
+    {
+        msg_Err( p_dec, "failed to link decode out pad" );
+        GST_ELEMENT_ERROR( p_sys->p_decoder, STREAM, FAILED,
+                ( "vlc stream error" ), NULL );
+    }
+
+    gst_object_unref( p_pad );
+}
+
+/* Sets the video output format */
+static bool set_vout_format( GstStructure* p_str,
+        const es_format_t *restrict p_infmt, es_format_t *restrict p_outfmt )
+{
+    video_format_t *p_voutfmt = &p_outfmt->video;
+    const video_format_t *p_vinfmt = &p_infmt->video;
+    gboolean b_ret;
+
+    /* We are interested in system memory raw buffers for now,
+     * but support for opaque data formats can also be added.
+     * For eg. when using HW decoders for zero-copy */
+    p_outfmt->i_codec = vlc_fourcc_GetCodecFromString(
+            VIDEO_ES,
+            gst_structure_get_string( p_str, "format" ) );
+    if( !p_outfmt->i_codec )
+        return false;
+
+    gst_structure_get_int( p_str, "width", &p_voutfmt->i_width );
+    gst_structure_get_int( p_str, "height", &p_voutfmt->i_height );
+
+    b_ret = gst_structure_get_fraction( p_str,
+            "pixel-aspect-ratio",
+            &p_voutfmt->i_sar_num,
+            &p_voutfmt->i_sar_den );
+
+    if( !b_ret || !p_voutfmt->i_sar_num ||
+            !p_voutfmt->i_sar_den )
+    {
+        p_voutfmt->i_sar_num = 1;
+        p_voutfmt->i_sar_den = 1;
+    }
+
+    b_ret = gst_structure_get_fraction( p_str, "framerate",
+            &p_voutfmt->i_frame_rate,
+            &p_voutfmt->i_frame_rate_base );
+
+    if( !b_ret || !p_voutfmt->i_frame_rate ||
+            !p_voutfmt->i_frame_rate_base )
+    {
+        p_voutfmt->i_frame_rate = p_vinfmt->i_frame_rate;
+        p_voutfmt->i_frame_rate_base = p_vinfmt->i_frame_rate_base;
+    }
+
+    return true;
+}
+
+static bool set_out_fmt( decoder_t *p_dec, GstPad *p_pad )
+{
+    GstCaps *p_caps = gst_pad_get_current_caps( p_pad );
+    decoder_sys_t *p_sys = p_dec->p_sys;
+    GstStructure *p_str;
+
+    if( !gst_video_info_from_caps( &p_sys->vinfo,
+                p_caps ) )
+    {
+        msg_Err( p_dec, "failed to get video info from caps" );
+        gst_caps_unref( p_caps );
+        GST_ELEMENT_ERROR( p_sys->p_decoder, STREAM, FAILED,
+                ( "vlc stream error" ), NULL );
+        return false;
+    }
+
+    p_str = gst_caps_get_structure( p_caps, 0 );
+
+    if( !set_vout_format( p_str, &p_dec->fmt_in, &p_dec->fmt_out ) )
+    {
+        msg_Err( p_dec, "failed to set out format" );
+        gst_caps_unref( p_caps );
+        GST_ELEMENT_ERROR( p_sys->p_decoder, STREAM, FAILED,
+                ( "vlc stream error" ), NULL );
+        return false;
+    }
+
+    gst_caps_unref( p_caps );
+    return true;
+}
+
+/* Emitted by decodebin and links decodebin to fakesink.
+ * Since only one elementary codec stream is fed to decodebin,
+ * this signal cannot be emitted more than once. */
+static void pad_added_cb( GstElement *p_ele, GstPad *p_pad, gpointer p_data )
+{
+    VLC_UNUSED( p_ele );
+    decoder_t *p_dec = p_data;
+    decoder_sys_t *p_sys = p_dec->p_sys;
+
+    if( likely( gst_pad_has_current_caps( p_pad ) ) )
+    {
+        GstPad *p_sinkpad;
+
+        if( !set_out_fmt( p_dec, p_pad ) )
+            return;
+
+        p_sinkpad = gst_element_get_static_pad(
+                p_sys->p_decode_out, "sink" );
+        gst_pad_link( p_pad, p_sinkpad );
+        gst_object_unref( p_sinkpad );
+    }
+    else
+    {
+        msg_Err( p_dec, "decodebin src pad has no caps" );
+        GST_ELEMENT_ERROR( p_sys->p_decoder, STREAM, FAILED,
+                ( "vlc stream error" ), NULL );
+    }
+}
+
+/* Emitted by fakesink for every buffer and sets the
+ * output format (if not set). Adds the buffer to the queue */
+static void frame_handoff_cb( GstElement *p_ele, GstBuffer *p_buf,
+        GstPad *p_pad, gpointer p_data )
+{
+    VLC_UNUSED( p_ele );
+    decoder_t *p_dec = p_data;
+    decoder_sys_t *p_sys = p_dec->p_sys;
+
+    if( unlikely( p_dec->fmt_out.i_codec == 0 ) )
+    {
+        if( !gst_pad_has_current_caps( p_pad ) )
+        {
+            msg_Err( p_dec, "fakesink pad has no caps" );
+            GST_ELEMENT_ERROR( p_sys->p_decoder, STREAM, FAILED,
+                    ( "vlc stream error" ), NULL );
+            return;
+        }
+
+        if( !set_out_fmt( p_dec, p_pad ) )
+            return;
+    }
+
+    /* Push the buffer to the queue */
+    gst_atomic_queue_push( p_sys->p_que, gst_buffer_ref( p_buf ) );
+}
+
+/* Copy the frame data from the GstBuffer (from decoder)
+ * to the picture obtained from downstream in VLC.
+ * TODO(Zero-Copy): This function should be avoided as much
+ * as possible, since it involves a complete frame copy. */
+static void gst_CopyPicture( picture_t *p_pic, GstVideoFrame *p_frame )
+{
+    int i_plane, i_planes, i_line, i_dst_stride, i_src_stride;
+    uint8_t *p_dst, *p_src;
+    int i_w, i_h;
+
+    i_planes = p_pic->i_planes;
+    for( i_plane = 0; i_plane < i_planes; i_plane++ )
+    {
+        p_dst = p_pic->p[i_plane].p_pixels;
+        p_src = GST_VIDEO_FRAME_PLANE_DATA( p_frame, i_plane );
+        i_dst_stride = p_pic->p[i_plane].i_pitch;
+        i_src_stride = GST_VIDEO_FRAME_PLANE_STRIDE( p_frame, i_plane );
+
+        i_w = GST_VIDEO_FRAME_COMP_WIDTH( p_frame,
+                i_plane ) * GST_VIDEO_FRAME_COMP_PSTRIDE( p_frame, i_plane );
+        i_h = GST_VIDEO_FRAME_COMP_HEIGHT( p_frame, i_plane );
+
+        for( i_line = 0;
+                i_line < __MIN( p_pic->p[i_plane].i_lines, i_h );
+                i_line++ )
+        {
+            memcpy( p_dst, p_src, i_w );
+            p_src += i_src_stride;
+            p_dst += i_dst_stride;
+        }
+    }
+}
+
+/* Check if the element can use this caps */
+static gint find_decoder_func( gconstpointer p_p1, gconstpointer p_p2 )
+{
+    GstElementFactory *p_factory;
+    sink_src_caps_t *p_caps;
+
+    p_factory = ( GstElementFactory* )p_p1;
+    p_caps = ( sink_src_caps_t* )p_p2;
+
+    return !( gst_element_factory_can_sink_any_caps( p_factory,
+                p_caps->p_sinkcaps ) &&
+            gst_element_factory_can_src_any_caps( p_factory,
+                p_caps->p_srccaps ) );
+}
+
+static bool default_msg_handler( decoder_t *p_dec, GstMessage *p_msg )
+{
+    bool err = false;
+
+    switch( GST_MESSAGE_TYPE( p_msg ) ){
+    case GST_MESSAGE_ERROR:
+        {
+            gchar  *psz_debug;
+            GError *p_error;
+
+            gst_message_parse_error( p_msg, &p_error, &psz_debug );
+            g_free( psz_debug );
+
+            msg_Err( p_dec, "Error from %s: %s",
+                    GST_ELEMENT_NAME( GST_MESSAGE_SRC( p_msg ) ),
+                    p_error->message );
+            g_error_free( p_error );
+            err = true;
+        }
+        break;
+    case GST_MESSAGE_WARNING:
+        {
+            gchar  *psz_debug;
+            GError *p_error;
+
+            gst_message_parse_warning( p_msg, &p_error, &psz_debug );
+            g_free( psz_debug );
+
+            msg_Warn( p_dec, "Warning from %s: %s",
+                    GST_ELEMENT_NAME( GST_MESSAGE_SRC( p_msg ) ),
+                    p_error->message );
+            g_error_free( p_error );
+        }
+        break;
+    case GST_MESSAGE_INFO:
+        {
+            gchar  *psz_debug;
+            GError *p_error;
+
+            gst_message_parse_info( p_msg, &p_error, &psz_debug );
+            g_free( psz_debug );
+
+            msg_Info( p_dec, "Info from %s: %s",
+                    GST_ELEMENT_NAME( GST_MESSAGE_SRC( p_msg ) ),
+                    p_error->message );
+            g_error_free( p_error );
+        }
+        break;
+    default:
+        break;
+    }
+
+    return err;
+}
+
+/*****************************************************************************
+ * OpenDecoder: probe the decoder and return score
+ *****************************************************************************/
+static int OpenDecoder( vlc_object_t *p_this )
+{
+    decoder_t *p_dec = ( decoder_t* )p_this;
+    decoder_sys_t *p_sys;
+    GstStateChangeReturn i_ret;
+    gboolean b_ret;
+    sink_src_caps_t caps = { NULL, NULL };
+    GstStructure *p_str;
+    GstAppSrcCallbacks cb;
+    int i_rval = VLC_SUCCESS;
+    GList *p_list;
+    bool dbin;
+
+#define VLC_GST_CHECK( r, v, s, t ) \
+    { if( r == v ){ msg_Err( p_dec, s ); i_rval = t; goto fail; } }
+
+    vlc_gst_init( );
+
+    p_str = vlc_to_gst_fmt( &p_dec->fmt_in );
+    if( !p_str )
+        return VLC_EGENERIC;
+
+    /* Allocate the memory needed to store the decoder's structure */
+    p_sys = p_dec->p_sys = calloc( 1, sizeof( *p_sys ) );
+    if( p_sys == NULL )
+    {
+        gst_structure_free( p_str );
+        return VLC_ENOMEM;
+    }
+
+    dbin = var_CreateGetBool( p_dec, "use-decodebin" );
+    msg_Dbg( p_dec, "Using decodebin? %s", dbin ? "yes ":"no" );
+
+    caps.p_sinkcaps = gst_caps_new_empty( );
+    gst_caps_append_structure( caps.p_sinkcaps, p_str );
+    /* Currently supports only system memory raw output format */
+    caps.p_srccaps = gst_caps_new_empty_simple( "video/x-raw" );
+
+    /* Get the list of all the available gstreamer decoders */
+    p_list = gst_element_factory_list_get_elements(
+            GST_ELEMENT_FACTORY_TYPE_DECODER, GST_RANK_MARGINAL );
+    VLC_GST_CHECK( p_list, NULL, "no decoder list found", VLC_ENOMOD );
+    if( !dbin )
+    {
+        GList *p_l;
+        /* Sort them as per ranks */
+        p_list = g_list_sort( p_list, gst_plugin_feature_rank_compare_func );
+        VLC_GST_CHECK( p_list, NULL, "failed to sort decoders list",
+                VLC_ENOMOD );
+        p_l = g_list_find_custom( p_list, &caps, find_decoder_func );
+        VLC_GST_CHECK( p_l, NULL, "no suitable decoder found",
+                VLC_ENOMOD );
+        /* create the decoder with highest rank */
+        p_sys->p_decode_in = gst_element_factory_create(
+                ( GstElementFactory* )p_l->data, NULL );
+        VLC_GST_CHECK( p_sys->p_decode_in, NULL,
+                "failed to create decoder", VLC_ENOMOD );
+    }
+    else
+    {
+        GList *p_l;
+        /* Just check if any suitable decoder exists, rest will be
+         * handled by decodebin */
+        p_l = g_list_find_custom( p_list, &caps, find_decoder_func );
+        VLC_GST_CHECK( p_l, NULL, "no suitable decoder found",
+                VLC_ENOMOD );
+    }
+    gst_plugin_feature_list_free( p_list );
+    p_list = NULL;
+    gst_caps_unref( caps.p_srccaps );
+    caps.p_srccaps = NULL;
+
+    p_sys->b_prerolled = false;
+    p_sys->b_running = false;
+
+    /* Queue: GStreamer thread will dump buffers into this queue,
+     * DecodeBlock() will pop out the buffers from the queue */
+    p_sys->p_que = gst_atomic_queue_new( 0 );
+    VLC_GST_CHECK( p_sys->p_que, NULL, "failed to create queue",
+            VLC_ENOMEM );
+
+    p_sys->p_decode_src = gst_element_factory_make( "appsrc", NULL );
+    VLC_GST_CHECK( p_sys->p_decode_src, NULL, "appsrc not found",
+            VLC_ENOMOD );
+    g_object_set( G_OBJECT( p_sys->p_decode_src ), "caps", caps.p_sinkcaps,
+            "block", FALSE, "emit-signals", TRUE, "format", GST_FORMAT_BYTES,
+            "stream-type", GST_APP_STREAM_TYPE_SEEKABLE,
+            /* Making DecodeBlock() to block on appsrc with max queue size of 1 byte.
+             * This will make the push_buffer() tightly coupled with the buffer
+             * flow from appsrc -> decoder. push_buffer() will only return when
+             * the same buffer it just fed to appsrc has also been fed to the
+             * decoder element as well */
+            "block", TRUE, "max-bytes", ( guint64 )1, NULL );
+    gst_caps_unref( caps.p_sinkcaps );
+    caps.p_sinkcaps = NULL;
+    cb.enough_data = cb.need_data = NULL;
+    cb.seek_data = seek_data_cb;
+    gst_app_src_set_callbacks( GST_APP_SRC( p_sys->p_decode_src ),
+            &cb, p_dec, NULL );
+
+    if( dbin )
+    {
+        p_sys->p_decode_in = gst_element_factory_make( "decodebin", NULL );
+        VLC_GST_CHECK( p_sys->p_decode_in, NULL, "decodebin not found",
+                VLC_ENOMOD );
+        //g_object_set( G_OBJECT( p_sys->p_decode_in ),
+        //"max-size-buffers", 2, NULL );
+        g_signal_connect( G_OBJECT( p_sys->p_decode_in ), "pad-added",
+                G_CALLBACK( pad_added_cb ), p_dec );
+        g_signal_connect( G_OBJECT( p_sys->p_decode_in ), "no-more-pads",
+                G_CALLBACK( no_more_pads_cb ), p_dec );
+    }
+
+    /* fakesink: will emit signal for every available buffer */
+    p_sys->p_decode_out = gst_element_factory_make( "fakesink", NULL );
+    VLC_GST_CHECK( p_sys->p_decode_out, NULL, "fakesink not found",
+            VLC_ENOMOD );
+    /* connect to the signal with the callback */
+    g_object_set( G_OBJECT( p_sys->p_decode_out ), "sync", FALSE,
+            "enable-last-sample", FALSE, "signal-handoffs", TRUE, NULL );
+    g_signal_connect( G_OBJECT( p_sys->p_decode_out ), "handoff",
+            G_CALLBACK( frame_handoff_cb ), p_dec );
+
+    p_sys->p_decoder = GST_ELEMENT( gst_bin_new( "decoder" ) );
+    VLC_GST_CHECK( p_sys->p_decoder, NULL, "bin not found", VLC_ENOMOD );
+    p_sys->p_bus = gst_bus_new( );
+    VLC_GST_CHECK( p_sys->p_bus, NULL, "failed to create bus",
+            VLC_ENOMOD );
+    gst_element_set_bus( p_sys->p_decoder, p_sys->p_bus );
+
+    gst_bin_add_many( GST_BIN( p_sys->p_decoder ),
+            p_sys->p_decode_src, p_sys->p_decode_in,
+            p_sys->p_decode_out, NULL );
+    gst_object_ref( p_sys->p_decode_src );
+    gst_object_ref( p_sys->p_decode_in );
+    gst_object_ref( p_sys->p_decode_out );
+
+    b_ret = gst_element_link( p_sys->p_decode_src, p_sys->p_decode_in );
+    VLC_GST_CHECK( b_ret, FALSE, "failed to link src <-> in",
+            VLC_EGENERIC );
+
+    if( !dbin )
+    {
+        b_ret = gst_element_link( p_sys->p_decode_in, p_sys->p_decode_out );
+        VLC_GST_CHECK( b_ret, FALSE, "failed to link in <-> out",
+                VLC_EGENERIC );
+    }
+
+    p_dec->fmt_out.i_cat = p_dec->fmt_in.i_cat;
+
+    /* set the pipeline to playing */
+    i_ret = gst_element_set_state( p_sys->p_decoder, GST_STATE_PLAYING );
+    VLC_GST_CHECK( i_ret, GST_STATE_CHANGE_FAILURE,
+            "set state failure", VLC_EGENERIC );
+    p_sys->b_running = true;
+
+    /* Force packetized for now */
+    p_dec->b_need_packetized = true;
+    /* Set callbacks */
+    p_dec->pf_decode_video = DecodeBlock;
+
+    return VLC_SUCCESS;
+
+fail:
+    if( caps.p_sinkcaps )
+        gst_caps_unref( caps.p_sinkcaps );
+    if( caps.p_srccaps )
+        gst_caps_unref( caps.p_srccaps );
+    if( p_list )
+        gst_plugin_feature_list_free( p_list );
+    CloseDecoder( ( vlc_object_t* )p_dec );
+    return i_rval;
+}
+
+/* Decode */
+static picture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
+{
+    block_t *p_block;
+    picture_t *p_pic = NULL;
+    decoder_sys_t *p_sys = p_dec->p_sys;
+    GstMessage *p_msg;
+    gboolean b_ret;
+    GstBuffer *p_buf;
+
+    if( !pp_block )
+        return NULL;
+
+    p_block = *pp_block;
+
+    if( !p_block )
+        goto check_messages;
+
+    if( unlikely( p_block->i_flags & (BLOCK_FLAG_DISCONTINUITY |
+                    BLOCK_FLAG_CORRUPTED ) ) )
+    {
+        if( p_block->i_flags & BLOCK_FLAG_DISCONTINUITY )
+        {
+            GstBuffer *p_buffer;
+            /* Send a new segment event. Seeking position is
+             * irrelevant in this case, as the main motive for a
+             * seek here, is to tell the elements to start flushing
+             * and start accepting buffers from a new time segment */
+            b_ret = gst_element_seek_simple( p_sys->p_decoder,
+                    GST_FORMAT_BYTES, GST_SEEK_FLAG_FLUSH, 0 );
+            msg_Dbg( p_dec, "new segment event : %d", b_ret );
+
+            /* flush the output buffers from the queue */
+            while( ( p_buffer = gst_atomic_queue_pop( p_sys->p_que ) ) )
+                gst_buffer_unref( p_buffer );
+
+            p_sys->b_prerolled = false;
+        }
+
+        block_Release( p_block );
+        goto done;
+    }
+
+    if( likely( p_block->i_buffer ) )
+    {
+        p_buf = gst_buffer_new_wrapped_full( GST_MEMORY_FLAG_READONLY,
+                p_block->p_start, p_block->i_size,
+                p_block->p_buffer - p_block->p_start, p_block->i_buffer,
+                p_block, ( GDestroyNotify )block_Release );
+        if( unlikely( p_buf == NULL ) )
+        {
+            msg_Err( p_dec, "failed to create input gstbuffer" );
+            p_dec->b_error = true;
+            block_Release( p_block );
+            goto done;
+        }
+
+        if( p_block->i_dts > VLC_TS_INVALID )
+            GST_BUFFER_DTS( p_buf ) = gst_util_uint64_scale( p_block->i_dts,
+                    GST_SECOND, GST_MSECOND );
+
+        if( p_block->i_pts <= VLC_TS_INVALID )
+            GST_BUFFER_PTS( p_buf ) = GST_BUFFER_DTS( p_buf );
+        else
+            GST_BUFFER_PTS( p_buf ) = gst_util_uint64_scale( p_block->i_pts,
+                    GST_SECOND, GST_MSECOND );
+
+        if( p_block->i_length > VLC_TS_INVALID )
+            GST_BUFFER_DURATION( p_buf ) = gst_util_uint64_scale(
+                    p_block->i_length, GST_SECOND, GST_MSECOND );
+
+        if( p_dec->fmt_in.video.i_frame_rate  &&
+                p_dec->fmt_in.video.i_frame_rate_base )
+            GST_BUFFER_DURATION( p_buf ) = gst_util_uint64_scale( GST_SECOND,
+                    p_dec->fmt_in.video.i_frame_rate_base,
+                    p_dec->fmt_in.video.i_frame_rate );
+
+        /* Give the input buffer to GStreamer Bin.
+         *
+         *  libvlc                      libvlc
+         *    \ (i/p)              (o/p) ^
+         *     \                        /
+         *   ___v____GSTREAMER BIN_____/____
+         *  |                               |
+         *  |   appsrc-->decode-->fakesink  |
+         *  |_______________________________|
+         *
+         * * * * * * * * * * * * * * * * * * * * */
+        if( unlikely( gst_app_src_push_buffer(
+                        GST_APP_SRC_CAST( p_sys->p_decode_src ), p_buf )
+                    != GST_FLOW_OK ) )
+        {
+            /* block will be released internally,
+             * when gst_buffer_unref() is called */
+            p_dec->b_error = true;
+            msg_Err( p_dec, "failed to push buffer" );
+            goto done;
+        }
+    }
+    else
+        block_Release( p_block );
+
+check_messages:
+    /* Poll for any messages, errors */
+    p_msg = gst_bus_pop_filtered( p_sys->p_bus,
+            GST_MESSAGE_ASYNC_DONE | GST_MESSAGE_ERROR |
+            GST_MESSAGE_EOS | GST_MESSAGE_WARNING |
+            GST_MESSAGE_INFO );
+    if( p_msg )
+    {
+        switch( GST_MESSAGE_TYPE( p_msg ) ){
+        case GST_MESSAGE_EOS:
+            /* for debugging purpose */
+            msg_Warn( p_dec, "got unexpected eos" );
+            break;
+        /* First buffer received */
+        case GST_MESSAGE_ASYNC_DONE:
+            /* for debugging purpose */
+            p_sys->b_prerolled = true;
+            msg_Dbg( p_dec, "Pipeline is prerolled" );
+            break;
+        default:
+            p_dec->b_error = default_msg_handler( p_dec, p_msg );
+            if( p_dec->b_error )
+            {
+                gst_message_unref( p_msg );
+                goto done;
+            }
+            break;
+        }
+        gst_message_unref( p_msg );
+    }
+
+    /* Look for any output buffers in the queue */
+    if( gst_atomic_queue_peek( p_sys->p_que ) )
+    {
+        GstVideoFrame frame;
+
+        /* Get a new picture */
+        p_pic = decoder_NewPicture( p_dec );
+        if( !p_pic )
+            goto done;
+
+        p_buf = GST_BUFFER_CAST(
+                gst_atomic_queue_pop( p_sys->p_que ) );
+
+        if( likely( GST_BUFFER_PTS_IS_VALID( p_buf ) ) )
+            p_pic->date = gst_util_uint64_scale(
+                    GST_BUFFER_PTS( p_buf ), GST_MSECOND, GST_SECOND );
+        else
+            msg_Warn( p_dec, "Gst Buffer has no timestamp" );
+
+        if( unlikely( !gst_video_frame_map( &frame,
+                        &p_sys->vinfo, p_buf, GST_MAP_READ ) ) )
+        {
+            msg_Err( p_dec, "failed to map gst video frame" );
+            gst_buffer_unref( p_buf );
+            p_dec->b_error = true;
+            goto done;
+        }
+
+        gst_CopyPicture( p_pic, &frame );
+        gst_video_frame_unmap( &frame );
+        gst_buffer_unref( p_buf );
+    }
+
+done:
+    *pp_block = NULL;
+    return p_pic;
+}
+
+/* Close the decoder instance */
+static void CloseDecoder( vlc_object_t *p_this )
+{
+    decoder_t *p_dec = ( decoder_t* )p_this;
+    decoder_sys_t *p_sys = p_dec->p_sys;
+
+    if( p_sys->b_running )
+    {
+        GstMessage *p_msg;
+        GstFlowReturn i_ret;
+
+        /* Send EOS to the pipeline */
+        i_ret = gst_app_src_end_of_stream(
+                GST_APP_SRC_CAST( p_sys->p_decode_src ) );
+        msg_Dbg( p_dec, "app src eos: %s", gst_flow_get_name( i_ret ) );
+
+        /* and catch it on the bus with a timeout */
+        p_msg = gst_bus_timed_pop_filtered( p_sys->p_bus,
+                2000000000ULL, GST_MESSAGE_EOS | GST_MESSAGE_ERROR );
+
+        if( p_msg )
+        {
+            switch( GST_MESSAGE_TYPE( p_msg ) ){
+            case GST_MESSAGE_EOS:
+                msg_Dbg( p_dec, "got eos" );
+                break;
+            default:
+                p_dec->b_error = default_msg_handler( p_dec, p_msg );
+                if( p_dec->b_error )
+                    msg_Warn( p_dec, "pipeline may not close gracefully" );
+                break;
+            }
+
+            gst_message_unref( p_msg );
+        }
+        else
+            msg_Warn( p_dec,
+                    "no message, pipeline may not close gracefully" );
+    }
+
+    /* Remove any left-over buffers from the queue */
+    if( p_sys->p_que )
+    {
+        GstBuffer *p_buf;
+        while( ( p_buf = gst_atomic_queue_pop( p_sys->p_que ) ) )
+            gst_buffer_unref( p_buf );
+        gst_atomic_queue_unref( p_sys->p_que );
+    }
+
+    if( p_sys->b_running &&
+            gst_element_set_state( p_sys->p_decoder, GST_STATE_NULL )
+            != GST_STATE_CHANGE_SUCCESS )
+        msg_Warn( p_dec,
+                "failed to change the state to NULL," \
+                "pipeline may not close gracefully" );
+
+    if( p_sys->p_bus )
+        gst_object_unref( p_sys->p_bus );
+    if( p_sys->p_decode_src )
+        gst_object_unref( p_sys->p_decode_src );
+    if( p_sys->p_decode_in )
+        gst_object_unref( p_sys->p_decode_in );
+    if( p_sys->p_decode_out )
+        gst_object_unref( p_sys->p_decode_out );
+    if( p_sys->p_decoder )
+        gst_object_unref( p_sys->p_decoder );
+
+    free( p_sys );
+}

po/POTFILES.in

@@ -372,6 +372,7 @@ modules/codec/fdkaac.c
 modules/codec/flac.c
 modules/codec/fluidsynth.c
 modules/codec/g711.c
+modules/codec/gstdecode.c
 modules/codec/jpeg.c
 modules/codec/kate.c
 modules/codec/libass.c