png: add encoder

modules/codec/png.c

@@ -33,12 +33,31 @@
 #include <vlc_codec.h>
 #include <png.h>
 
+/* PNG_SYS_COMMON_MEMBERS:
+ * members common to encoder and decoder descriptors
+ */
+#define PNG_SYS_COMMON_MEMBERS                              \
+/**@{*/                                                     \
+    bool b_error;                                           \
+    vlc_object_t *p_obj;                                    \
+/**@}*/                                                     \
+
+/*
+ * png common descriptor
+ */
+struct png_sys_t
+{
+    PNG_SYS_COMMON_MEMBERS
+};
+
+typedef struct png_sys_t png_sys_t;
+
 /*****************************************************************************
  * decoder_sys_t : png decoder descriptor
  *****************************************************************************/
 struct decoder_sys_t
 {
-    bool b_error;
+    PNG_SYS_COMMON_MEMBERS
 };
 
 /*****************************************************************************
@@ -49,6 +68,20 @@ static void CloseDecoder  ( vlc_object_t * );
 
 static picture_t *DecodeBlock  ( decoder_t *, block_t ** );
 
+/*
+ * png encoder descriptor
+ */
+struct encoder_sys_t
+{
+    PNG_SYS_COMMON_MEMBERS
+    int i_blocksize;
+};
+
+static int  OpenEncoder(vlc_object_t *);
+static void CloseEncoder(vlc_object_t *);
+
+static block_t *EncodeBlock(encoder_t *, picture_t *);
+
 /*****************************************************************************
  * Module descriptor
  *****************************************************************************/
@@ -59,6 +92,14 @@ vlc_module_begin ()
     set_capability( "decoder", 1000 )
     set_callbacks( OpenDecoder, CloseDecoder )
     add_shortcut( "png" )
+
+    /* encoder submodule */
+    add_submodule()
+    add_shortcut("png")
+    set_section(N_("Encoding"), NULL)
+    set_description(N_("PNG video encoder"))
+    set_capability("encoder", 1000)
+    set_callbacks(OpenEncoder, CloseEncoder)
 vlc_module_end ()
 
 /*****************************************************************************
@@ -78,6 +119,8 @@ static int OpenDecoder( vlc_object_t *p_this )
     if( ( p_dec->p_sys = malloc(sizeof(decoder_sys_t)) ) == NULL )
         return VLC_ENOMEM;
 
+    p_dec->p_sys->p_obj = p_this;
+
     /* Set output properties */
     p_dec->fmt_out.i_cat = VIDEO_ES;
     p_dec->fmt_out.i_codec = VLC_CODEC_RGBA;
@@ -101,17 +144,40 @@ static void user_read( png_structp p_png, png_bytep data, png_size_t i_length )
     p_block->i_buffer -= i_length;
 }
 
+static void user_flush( png_structp p_png )
+{
+    /* noop */
+    (void) p_png;
+}
+
+static void user_write( png_structp p_png, png_bytep data, png_size_t i_length )
+{
+    block_t *p_block = (block_t *)png_get_io_ptr( p_png );
+    if( i_length > p_block->i_buffer ) {
+        char err_str[64];
+        snprintf( err_str, sizeof(err_str),
+                  "block size %zu too small for %zu encoded bytes",
+                  p_block->i_buffer, i_length );
+        png_error( p_png, err_str );
+        return;
+    }
+
+    memcpy( p_block->p_buffer, data, i_length );
+    p_block->p_buffer += i_length;
+    p_block->i_buffer -= i_length;
+}
+
 static void user_error( png_structp p_png, png_const_charp error_msg )
 {
-    decoder_t *p_dec = (decoder_t *)png_get_error_ptr( p_png );
-    p_dec->p_sys->b_error = true;
-    msg_Err( p_dec, "%s", error_msg );
+    png_sys_t *p_sys = (png_sys_t *)png_get_error_ptr( p_png );
+    p_sys->b_error = true;
+    msg_Err( p_sys->p_obj, "%s", error_msg );
 }
 
 static void user_warning( png_structp p_png, png_const_charp warning_msg )
 {
-    decoder_t *p_dec = (decoder_t *)png_get_error_ptr( p_png );
-    msg_Warn( p_dec, "%s", warning_msg );
+    png_sys_t *p_sys = (png_sys_t *)png_get_error_ptr( p_png );
+    msg_Warn( p_sys->p_obj, "%s", warning_msg );
 }
 
 /****************************************************************************
@@ -253,3 +319,125 @@ static void CloseDecoder( vlc_object_t *p_this )
 
     free( p_sys );
 }
+
+static int OpenEncoder(vlc_object_t *p_this)
+{
+    encoder_t *p_enc = (encoder_t *) p_this;
+
+    if( p_enc->fmt_out.i_codec != VLC_CODEC_PNG )
+        return VLC_EGENERIC;
+
+    /* Allocate the memory needed to store the encoder's structure */
+    p_enc->p_sys = malloc( sizeof(encoder_sys_t) );
+    if( p_enc->p_sys  == NULL )
+        return VLC_ENOMEM;
+
+    p_enc->p_sys->p_obj = p_this;
+
+    p_enc->p_sys->i_blocksize = 3 * p_enc->fmt_in.video.i_visible_width *
+        p_enc->fmt_in.video.i_visible_height;
+
+    p_enc->fmt_in.i_codec = VLC_CODEC_RGB24;
+    p_enc->fmt_in.video.i_rmask = 0x000000ff;
+    p_enc->fmt_in.video.i_gmask = 0x0000ff00;
+    p_enc->fmt_in.video.i_bmask = 0x00ff0000;
+    p_enc->pf_encode_video = EncodeBlock;
+
+    return VLC_SUCCESS;
+}
+
+/*
+ * EncodeBlock
+ */
+static block_t *EncodeBlock(encoder_t *p_enc, picture_t *p_pic)
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    if( unlikely( !p_pic ) )
+    {
+        return NULL;
+    }
+
+    block_t *p_block = block_Alloc( p_sys->i_blocksize );
+    if( p_block == NULL )
+    {
+        return NULL;
+    }
+
+    png_structp p_png = png_create_write_struct( PNG_LIBPNG_VER_STRING, 0, 0, 0 );
+    if( p_png == NULL )
+    {
+        block_Release( p_block );
+        return NULL;
+    }
+
+    /* save buffer start */
+    uint8_t *p_start = p_block->p_buffer;
+    size_t i_start = p_block->i_buffer;
+
+    p_sys->b_error = false;
+    png_infop p_info = NULL;
+
+    /* libpng longjmp's there in case of error */
+    if( setjmp( png_jmpbuf( p_png ) ) )
+        goto error;
+
+    png_set_write_fn( p_png, p_block, user_write, user_flush );
+    png_set_error_fn( p_png, p_enc, user_error, user_warning );
+
+    p_info = png_create_info_struct( p_png );
+    if( p_info == NULL )
+        goto error;
+
+    png_infop p_end_info = png_create_info_struct( p_png );
+    if( p_end_info == NULL ) goto error;
+
+    const unsigned i_width = p_enc->fmt_in.video.i_visible_width;
+    const unsigned i_height = p_enc->fmt_in.video.i_visible_height;
+
+    png_set_IHDR( p_png, p_info,
+            i_width,
+            i_height,
+            8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
+            PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT );
+    if( p_sys->b_error ) goto error;
+
+    png_write_info( p_png, p_info );
+    if( p_sys->b_error ) goto error;
+
+    /* Encode picture */
+
+    for( unsigned i = 0; i < i_height; i++ )
+    {
+        png_write_row( p_png, p_pic->p->p_pixels + (i_width * i * 3));
+        if( p_sys->b_error ) goto error;
+    }
+
+    png_write_end( p_png, p_end_info );
+    if( p_sys->b_error ) goto error;
+
+    png_destroy_write_struct( &p_png, &p_info );
+
+    /* restore original buffer position */
+    p_block->p_buffer = p_start;
+    p_block->i_buffer = i_start;
+    return p_block;
+
+ error:
+
+    png_destroy_write_struct( &p_png, p_info ? &p_info : NULL );
+
+    block_Release(p_block);
+    return NULL;
+}
+
+/*****************************************************************************
+ * CloseEncoder: png encoder destruction
+ *****************************************************************************/
+static void CloseEncoder( vlc_object_t *p_this )
+{
+    encoder_t *p_enc = (encoder_t *)p_this;
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    free( p_sys );
+}