avcodec: add 'ffmpeg-hw-codec' to select a specific 'hw decoder'

Make it possible to select a specific 'hw decoder' module. Currently
only: vaapi, dxva2 and vdpau are supported choices.

modules/codec/avcodec/avcodec.c

@@ -130,6 +130,7 @@ vlc_module_begin ()
                  true )
     add_string( "ffmpeg-codec", NULL, CODEC_TEXT, CODEC_LONGTEXT, true )
     add_bool( "ffmpeg-hw", false, HW_TEXT, HW_LONGTEXT, false )
+    add_module( "ffmpeg-hw-codec", "hw decoder", "vaapi", HW_TEXT, HW_LONGTEXT, false )
 
 #if defined(FF_THREAD_FRAME)
     add_integer( "ffmpeg-threads", 0, THREADS_TEXT, THREADS_LONGTEXT, true );

modules/codec/avcodec/avcodec.h

@@ -147,7 +147,8 @@ int ffmpeg_OpenCodec( decoder_t *p_dec );
     "speedup for high definition streams." )
 
 #define HW_TEXT N_("Hardware decoding")
-#define HW_LONGTEXT N_("This allows hardware decoding when available.")
+#define HW_LONGTEXT N_("This allows hardware decoding when available. " \
+    "Curent choices are: 'none', 'dxva2', 'vaapi' and 'vdpau'. The default is: 'vaapi'" )
 
 #define THREADS_TEXT N_( "Threads" )
 #define THREADS_LONGTEXT N_( "Number of threads used for decoding, 0 meaning auto" )

modules/codec/avcodec/video.c

@@ -359,7 +359,8 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
 #endif
 
     const bool b_use_hw = var_CreateGetBool( p_dec, "ffmpeg-hw" );
-    if( b_use_hw &&
+    char *hw = var_CreateGetString( p_dec, "ffmpeg-hw-codec" ); /* FIXME */
+    if( (b_use_hw && (hw == NULL || strcasecmp( hw, "none" ))) &&
         (i_codec_id == CODEC_ID_MPEG1VIDEO || i_codec_id == CODEC_ID_MPEG2VIDEO ||
          i_codec_id == CODEC_ID_MPEG4 ||
          i_codec_id == CODEC_ID_H264 ||
@@ -382,6 +383,7 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
 #endif
         p_sys->p_context->get_format = ffmpeg_GetFormat;
     }
+    free(hw);
 
 #ifdef HAVE_AVCODEC_MT
     if( p_sys->p_context->thread_type & FF_THREAD_FRAME )
@@ -1151,7 +1153,7 @@ static vlc_va_t *vlc_va_New( vlc_object_t *parent, int codec_id,
     if( unlikely(p_va == NULL) )
         return NULL;
 
-    p_va->module = vlc_module_load( p_va, "hw decoder", "$avcodec-hw",
+    p_va->module = vlc_module_load( p_va, "hw decoder", "$ffmpeg-hw-codec",
                                     true, ffmpeg_va_Start, p_va,
                                     codec_id, fmt );
     if( p_va->module == NULL )