ref: 116b703442e52a5dca635b5050d3d7165d2c9662
parent: 26ff5e089106de677328d2b53d08a26d22af37e6
author: Timothy B. Terriberry <tterribe@xiph.org>
date: Sat Aug 10 07:19:33 EDT 2013
Add an API to parse picture tags. This makes it easier for applications to support album art. This is still relatively untested.
--- a/examples/opusfile_example.c
+++ b/examples/opusfile_example.c
@@ -93,6 +93,24 @@
else fprintf(_fp,"%li%s%c",(long)val,_spacer,SUFFIXES[shift]);
}
+/*A version of strncasecmp() that is guaranteed to only ignore the case of
+ ASCII characters.*/
+static int local_strncasecmp(const char *_a,const char *_b,int _n){+ int i;
+ for(i=0;i<_n;i++){+ int a;
+ int b;
+ int d;
+ a=_a[i];
+ b=_b[i];
+ if(a>='a'&&a<='z')a-='a'-'A';
+ if(b>='a'&&b<='z')b-='a'-'A';
+ d=a-b;
+ if(d)return d;
+ }
+ return 0;
+}
+
static void put_le32(unsigned char *_dst,opus_uint32 _x){_dst[0]=(unsigned char)(_x&0xFF);
_dst[1]=(unsigned char)(_x>>8&0xFF);
@@ -256,7 +274,28 @@
tags=op_tags(of,li);
fprintf(stderr," Encoded by: %s\n",tags->vendor);
for(ci=0;ci<tags->comments;ci++){- fprintf(stderr," %s\n",tags->user_comments[ci]);
+ const char *comment;
+ comment=tags->user_comments[ci];
+ if(local_strncasecmp(comment,"METADATA_BLOCK_PICTURE=",23)==0){+ OpusPictureTag pic;
+ int err;
+ err=opus_picture_tag_parse(&pic,comment);
+ fprintf(stderr," %.23s",comment);
+ if(err>=0){+ fprintf(stderr,"%u|%s|%s|%ux%ux%u",pic.type,pic.mime_type,
+ pic.description,pic.width,pic.height,pic.depth);
+ if(pic.colors!=0)fprintf(stderr,"/%u",pic.colors);
+ if(pic.format==OP_PIC_FORMAT_URL){+ fprintf(stderr,"|%s\n",pic.data);
+ }
+ else{+ fprintf(stderr,"|<%u bytes of image data>\n",pic.data_length);
+ }
+ opus_picture_tag_clear(&pic);
+ }
+ else fprintf(stderr,"<error parsing picture tag>\n");
+ }
+ else fprintf(stderr," %s\n",tags->user_comments[ci]);
}
fprintf(stderr,"\n");
if(!op_seekable(of)){--- a/include/opusfile.h
+++ b/include/opusfile.h
@@ -122,9 +122,10 @@
# pragma GCC visibility push(default)
# endif
-typedef struct OpusHead OpusHead;
-typedef struct OpusTags OpusTags;
-typedef struct OggOpusFile OggOpusFile;
+typedef struct OpusHead OpusHead;
+typedef struct OpusTags OpusTags;
+typedef struct OpusPictureTag OpusPictureTag;
+typedef struct OggOpusFile OggOpusFile;
/*Warning attributes for libopusfile functions.*/
# if OP_GNUC_PREREQ(3,4)
@@ -301,6 +302,87 @@
char *vendor;
};
+/**\name Picture tag image formats*/
+/*@{*/+
+/**The MIME type was not recognized, or the image data did not match the
+ declared MIME type.*/
+#define OP_PIC_FORMAT_UNKNOWN (-1)
+/**The MIME type indicates the image data is really a URL.*/
+#define OP_PIC_FORMAT_URL (0)
+/**The image is a JPEG.*/
+#define OP_PIC_FORMAT_JPEG (1)
+/**The image is a PNG.*/
+#define OP_PIC_FORMAT_PNG (2)
+/**The image is a GIF.*/
+#define OP_PIC_FORMAT_GIF (3)
+
+/*@}*/
+
+/**The contents of a METADATA_BLOCK_PICTURE tag.*/
+struct OpusPictureTag{+ /**The picture type according to the ID3v2 APIC frame:
+ <ol start="0">
+ <li>Other</li>
+ <li>32x32 pixels 'file icon' (PNG only)</li>
+ <li>Other file icon</li>
+ <li>Cover (front)</li>
+ <li>Cover (back)</li>
+ <li>Leaflet page</li>
+ <li>Media (e.g. label side of CD)</li>
+ <li>Lead artist/lead performer/soloist</li>
+ <li>Artist/performer</li>
+ <li>Conductor</li>
+ <li>Band/Orchestra</li>
+ <li>Composer</li>
+ <li>Lyricist/text writer</li>
+ <li>Recording Location</li>
+ <li>During recording</li>
+ <li>During performance</li>
+ <li>Movie/video screen capture</li>
+ <li>A bright colored fish</li>
+ <li>Illustration</li>
+ <li>Band/artist logotype</li>
+ <li>Publisher/Studio logotype</li>
+ </ol>
+ Others are reserved and should not be used.
+ There may only be one each of picture type 1 and 2 in a file.*/
+ opus_int32 type;
+ /**The MIME type of the picture, in printable ASCII characters 0x20-0x7E.
+ The MIME type may also be <code>"-->"</code> to signify that the data part
+ is a URL pointing to the picture instead of the picture data itself.
+ In this case, a terminating NUL is appended to the URL string in #data,
+ but #data_length is set to the length of the string excluding that
+ terminating NUL.*/
+ char *mime_type;
+ /**The description of the picture, in UTF-8.*/
+ char *description;
+ /**The width of the picture in pixels.*/
+ opus_uint32 width;
+ /**The height of the picture in pixels.*/
+ opus_uint32 height;
+ /**The color depth of the picture in bits-per-pixel (<em>not</em>
+ bits-per-channel).*/
+ opus_uint32 depth;
+ /**For indexed-color pictures (e.g., GIF), the number of colors used, or 0
+ for non-indexed pictures.*/
+ opus_uint32 colors;
+ /**The length of the picture data in bytes.*/
+ opus_uint32 data_length;
+ /**The binary picture data.*/
+ unsigned char *data;
+ /**The format of the picture data, if known.
+ One of
+ <ul>
+ <li>#OP_PIC_FORMAT_UNKNOWN,</li>
+ <li>#OP_PIC_FORMAT_URL,</li>
+ <li>#OP_PIC_FORMAT_JPEG,</li>
+ <li>#OP_PIC_FORMAT_PNG,</li>
+ <li>#OP_PIC_FORMAT_GIF, or</li>
+ </ul>.*/
+ int format;
+};
+
/**\name Functions for manipulating header data
These functions manipulate the #OpusHead and #OpusTags structures,
@@ -457,6 +539,51 @@
It will free all memory used by the structure members.
\param _tags The #OpusTags structure to clear.*/
void opus_tags_clear(OpusTags *_tags) OP_ARG_NONNULL(1);
+
+/**Parse a single METADATA_BLOCK_PICTURE tag.
+ This decodes the BASE64-encoded content of the tag and returns a structure
+ with the MIME type, description, image parameters (if known), and the
+ compressed image data.
+ If the MIME type indicates the presence of an image format we recognize
+ (JPEG, PNG, or GIF) and the actual image data contains the magic signature
+ associated with that format, then the OpusPictureTag::format field will be
+ set to the corresponding format.
+ This is provided as a convenience to avoid requiring applications to parse
+ the MIME type and/or do their own format detection for the commonly used
+ formats.
+ In this case, we also attempt to extract the image parameters directly from
+ the image data (overriding any that were present in the tag, which the
+ specification says applications are not meant to rely on).
+ The application must still provide its own support for actually decoding the
+ image data and, if applicable, retrieving that data from URLs.
+ \param[out] _pic Returns the parsed picture data.
+ No sanitation is done on the type, MIME type, or
+ description fields, so these might return invalid values.
+ The contents of this structure are left unmodified on
+ failure.
+ \param _tag The METADATA_BLOCK_PICTURE tag contents.
+ The leading "METADATA_BLOCK_PICTURE=" portion is optional,
+ to allow the function to be used on either directly on the
+ values in OpusTags::user_comments or on the return value
+ of opus_tags_query().
+ \return 0 on success or a negative value on error.
+ \retval #OP_ENOTFORMAT The METADATA_BLOCK_PICTURE contents were not valid.
+ \retval #OP_EFAULT A memory allocation failed.*/
+int opus_picture_tag_parse(OpusPictureTag *_pic,const char *_tag)
+ OP_ARG_NONNULL(1) OP_ARG_NONNULL(2);
+
+/**Initializes an #OpusPictureTag structure.
+ This should be called on a freshly allocated #OpusPictureTag structure
+ before attempting to use it.
+ \param _pic The #OpusPictureTag structure to initialize.*/
+void opus_picture_tag_init(OpusPictureTag *_pic) OP_ARG_NONNULL(1);
+
+/**Clears the #OpusPictureTag structure.
+ This should be called on an #OpusPictureTag structure after it is no longer
+ needed.
+ It will free all memory used by the structure members.
+ \param _pic The #OpusPictureTag structure to clear.*/
+void opus_picture_tag_clear(OpusPictureTag *_pic) OP_ARG_NONNULL(1);
/*@}*/
--- a/src/info.c
+++ b/src/info.c
@@ -31,6 +31,10 @@
return _data[0]|_data[1]<<8|_data[2]<<16|_data[3]<<24;
}
+static opus_uint32 op_parse_uint32be(const unsigned char *_data){+ return _data[3]|_data[2]<<8|_data[1]<<16|_data[0]<<24;
+}
+
int opus_head_parse(OpusHead *_head,const unsigned char *_data,size_t _len){OpusHead head;
if(_len<8)return OP_ENOTFORMAT;
@@ -325,4 +329,322 @@
}
}
return OP_FALSE;
+}
+
+static int op_is_jpeg(const unsigned char *_buf,size_t _buf_sz){+ return _buf_sz>=11&&memcmp(_buf,"\xFF\xD8\xFF\xE0",4)==0
+ &&(_buf[4]<<8|_buf[5])>=16&&memcmp(_buf+6,"JFIF",5)==0;
+}
+
+/*Tries to extract the width, height, bits per pixel, and palette size of a
+ JPEG.
+ On failure, simply leaves its outputs unmodified.*/
+static void op_extract_jpeg_params(const unsigned char *_buf,size_t _buf_sz,
+ opus_uint32 *_width,opus_uint32 *_height,
+ opus_uint32 *_depth,opus_uint32 *_colors,int *_has_palette){+ if(op_is_jpeg(_buf,_buf_sz)){+ size_t offs;
+ offs=2;
+ for(;;){+ size_t segment_len;
+ int marker;
+ while(offs<_buf_sz&&_buf[offs]!=0xFF)offs++;
+ while(offs<_buf_sz&&_buf[offs]==0xFF)offs++;
+ marker=_buf[offs];
+ offs++;
+ /*If we hit EOI* (end of image), or another SOI* (start of image),
+ or SOS (start of scan), then stop now.*/
+ if(offs>=_buf_sz||(marker>=0xD8&&marker<=0xDA))break;
+ /*RST* (restart markers): skip (no segment length).*/
+ else if(marker>=0xD0&&marker<=0xD7)continue;
+ /*Read the length of the marker segment.*/
+ if(_buf_sz-offs<2)break;
+ segment_len=_buf[offs]<<8|_buf[offs+1];
+ if(segment_len<2||_buf_sz-offs<segment_len)break;
+ if(marker==0xC0||(marker>0xC0&&marker<0xD0&&(marker&3)!=0)){+ /*Found a SOFn (start of frame) marker segment:*/
+ if(segment_len>=8){+ *_height=_buf[offs+3]<<8|_buf[offs+4];
+ *_width=_buf[offs+5]<<8|_buf[offs+6];
+ *_depth=_buf[offs+2]*_buf[offs+7];
+ *_colors=0;
+ *_has_palette=0;
+ }
+ break;
+ }
+ /*Other markers: skip the whole marker segment.*/
+ offs+=segment_len;
+ }
+ }
+}
+
+static int op_is_png(const unsigned char *_buf,size_t _buf_sz){+ return _buf_sz>=8&&memcmp(_buf,"\x89PNG\x0D\x0A\x1A\x0A",8)==0;
+}
+
+/*Tries to extract the width, height, bits per pixel, and palette size of a
+ PNG.
+ On failure, simply leaves its outputs unmodified.*/
+static void op_extract_png_params(const unsigned char *_buf,size_t _buf_sz,
+ opus_uint32 *_width,opus_uint32 *_height,
+ opus_uint32 *_depth,opus_uint32 *_colors,int *_has_palette){+ if(op_is_png(_buf,_buf_sz)){+ size_t offs;
+ offs=8;
+ while(_buf_sz-offs>=12){+ ogg_uint32_t chunk_len;
+ chunk_len=op_parse_uint32be(_buf+offs);
+ if(chunk_len>_buf_sz-(offs+12))break;
+ else if(chunk_len==13&&memcmp(_buf+offs+4,"IHDR",4)==0){+ int color_type;
+ *_width=op_parse_uint32be(_buf+offs+8);
+ *_height=op_parse_uint32be(_buf+offs+12);
+ color_type=_buf[offs+17];
+ if(color_type==3){+ *_depth=24;
+ *_has_palette=1;
+ }
+ else{+ int sample_depth;
+ sample_depth=_buf[offs+16];
+ if(color_type==0)*_depth=sample_depth;
+ else if(color_type==2)*_depth=sample_depth*3;
+ else if(color_type==4)*_depth=sample_depth*2;
+ else if(color_type==6)*_depth=sample_depth*4;
+ *_colors=0;
+ *_has_palette=0;
+ break;
+ }
+ }
+ else if(*_has_palette>0&&memcmp(_buf+offs+4,"PLTE",4)==0){+ *_colors=chunk_len/3;
+ break;
+ }
+ offs+=12+chunk_len;
+ }
+ }
+}
+
+static int op_is_gif(const unsigned char *_buf,size_t _buf_sz){+ return _buf_sz>=6&&(memcmp(_buf,"GIF87a",6)==0||memcmp(_buf,"GIF89a",6)==0);
+}
+
+/*Tries to extract the width, height, bits per pixel, and palette size of a
+ GIF.
+ On failure, simply leaves its outputs unmodified.*/
+static void op_extract_gif_params(const unsigned char *_buf,size_t _buf_sz,
+ opus_uint32 *_width,opus_uint32 *_height,
+ opus_uint32 *_depth,opus_uint32 *_colors,int *_has_palette){+ if(op_is_gif(_buf,_buf_sz)&&_buf_sz>=14){+ *_width=_buf[6]|_buf[7]<<8;
+ *_height=_buf[8]|_buf[9]<<8;
+ /*libFLAC hard-codes the depth to 24.*/
+ *_depth=24;
+ *_colors=1<<((_buf[10]&7)+1);
+ *_has_palette=1;
+ }
+}
+
+/*The actual implementation of opus_picture_tag_parse().
+ Unlike the public API, this function requires _pic to already be
+ initialized, modifies its contents before success is guaranteed, and assumes
+ the caller will clear it on error.*/
+static int opus_picture_tag_parse_impl(OpusPictureTag *_pic,const char *_tag,
+ unsigned char *_buf,size_t _buf_sz,size_t _base64_sz){+ opus_int32 picture_type;
+ opus_uint32 mime_type_length;
+ char *mime_type;
+ opus_uint32 description_length;
+ char *description;
+ opus_uint32 width;
+ opus_uint32 height;
+ opus_uint32 depth;
+ opus_uint32 colors;
+ opus_uint32 data_length;
+ opus_uint32 file_width;
+ opus_uint32 file_height;
+ opus_uint32 file_depth;
+ opus_uint32 file_colors;
+ int format;
+ int has_palette;
+ int colors_set;
+ size_t i;
+ /*Decode the BASE64 data.*/
+ for(i=0;i<_base64_sz;i++){+ opus_uint32 value;
+ int j;
+ for(j=0;j<4;j++){+ unsigned c;
+ unsigned d;
+ c=(unsigned char)_tag[4*i+j];
+ if(c=='+')d=62;
+ else if(c=='/')d=63;
+ else if(c>='0'&&c<='9')d=52+c-'0';
+ else if(c>='a'&&c<='z')d=26+c-'a';
+ else if(c>='A'&&c<='Z')d=c-'A';
+ else if(c=='='&&3*i+j>_buf_sz)d=0;
+ else return OP_ENOTFORMAT;
+ value=value<<6|d;
+ }
+ _buf[3*i]=(unsigned char)(value>>16);
+ if(3*i+1<_buf_sz){+ _buf[3*i+1]=(unsigned char)(value>>8);
+ if(3*i+2<_buf_sz)_buf[3*i+2]=(unsigned char)value;
+ }
+ }
+ i=0;
+ picture_type=op_parse_uint32be(_buf+i);
+ i+=4;
+ /*Extract the MIME type.*/
+ mime_type_length=op_parse_uint32be(_buf+i);
+ i+=4;
+ if(mime_type_length>_buf_sz-32)return OP_ENOTFORMAT;
+ mime_type=(char *)_ogg_malloc(sizeof(*_pic->mime_type)*(mime_type_length+1));
+ if(mime_type==NULL)return OP_EFAULT;
+ memcpy(mime_type,_buf+i,sizeof(*mime_type)*mime_type_length);
+ mime_type[mime_type_length]='\0';
+ _pic->mime_type=mime_type;
+ i+=mime_type_length;
+ /*Extract the description string.*/
+ description_length=op_parse_uint32be(_buf+i);
+ i+=4;
+ if(description_length>_buf_sz-mime_type_length-32)return OP_ENOTFORMAT;
+ description=
+ (char *)_ogg_malloc(sizeof(*_pic->mime_type)*(description_length+1));
+ if(description==NULL)return OP_EFAULT;
+ memcpy(description,_buf+i,sizeof(*description)*description_length);
+ description[description_length]='\0';
+ _pic->description=description;
+ i+=description_length;
+ /*Extract the remaining fields.*/
+ width=op_parse_uint32be(_buf+i);
+ i+=4;
+ height=op_parse_uint32be(_buf+i);
+ i+=4;
+ depth=op_parse_uint32be(_buf+i);
+ i+=4;
+ colors=op_parse_uint32be(_buf+i);
+ i+=4;
+ /*If one of these is set, they all must be, but colors==0 is a valid value.*/
+ colors_set=width!=0||height!=0||depth!=0||colors!=0;
+ if(width==0||height==0||depth==0&&colors_set)return OP_ENOTFORMAT;
+ data_length=op_parse_uint32be(_buf+i);
+ i+=4;
+ if(data_length>_buf_sz-i)return OP_ENOTFORMAT;
+ /*Trim extraneous data so we don't copy it below.*/
+ _buf_sz=i+data_length;
+ /*Attempt to determine the image format.*/
+ format=OP_PIC_FORMAT_UNKNOWN;
+ if(mime_type_length==3&&strcmp(mime_type,"-->")==0){+ format=OP_PIC_FORMAT_URL;
+ /*Picture type 1 must be a 32x32 PNG.*/
+ if(picture_type==1&&(width!=0||height!=0)&&(width!=32||height!=32)){+ return OP_ENOTFORMAT;
+ }
+ /*Append a terminating NUL for the convenience of our callers.*/
+ _buf[_buf_sz++]='\0';
+ }
+ else{+ if(mime_type_length==10
+ &&op_strncasecmp(mime_type,"image/jpeg",mime_type_length)==0){+ if(op_is_jpeg(_buf+i,data_length))format=OP_PIC_FORMAT_JPEG;
+ }
+ else if(mime_type_length==9
+ &&op_strncasecmp(mime_type,"image/png",mime_type_length)==0){+ if(op_is_png(_buf+i,data_length))format=OP_PIC_FORMAT_PNG;
+ }
+ else if(mime_type_length==9
+ &&op_strncasecmp(mime_type,"image/gif",mime_type_length)==0){+ if(op_is_gif(_buf+i,data_length))format=OP_PIC_FORMAT_GIF;
+ }
+ else if(mime_type_length==0||(mime_type_length==6
+ &&op_strncasecmp(mime_type,"image/",mime_type_length)==0)){+ if(op_is_jpeg(_buf+i,data_length))format=OP_PIC_FORMAT_JPEG;
+ else if(op_is_png(_buf+i,data_length))format=OP_PIC_FORMAT_PNG;
+ else if(op_is_gif(_buf+i,data_length))format=OP_PIC_FORMAT_GIF;
+ }
+ file_width=file_height=file_depth=file_colors=0;
+ has_palette=-1;
+ switch(format){+ case OP_PIC_FORMAT_JPEG:{+ op_extract_jpeg_params(_buf+i,data_length,
+ &file_width,&file_height,&file_depth,&file_colors,&has_palette);
+ }break;
+ case OP_PIC_FORMAT_PNG:{+ op_extract_png_params(_buf+i,data_length,
+ &file_width,&file_height,&file_depth,&file_colors,&has_palette);
+ }break;
+ case OP_PIC_FORMAT_GIF:{+ op_extract_gif_params(_buf+i,data_length,
+ &file_width,&file_height,&file_depth,&file_colors,&has_palette);
+ }break;
+ }
+ if(has_palette>=0){+ /*If we successfully extracted these parameters from the image, override
+ any declared values.*/
+ width=file_width;
+ height=file_height;
+ depth=file_depth;
+ colors=file_colors;
+ }
+ /*Picture type 1 must be a 32x32 PNG.*/
+ if(picture_type==1&&(format!=OP_PIC_FORMAT_PNG||width!=32||height!=32)){+ return OP_ENOTFORMAT;
+ }
+ }
+ /*Adjust _buf_sz instead of using data_length to capture the terminating NUL
+ for URLs.*/
+ _buf_sz-=i;
+ memmove(_buf,_buf+i,sizeof(*_buf)*_buf_sz);
+ _buf=(unsigned char *)_ogg_realloc(_buf,_buf_sz);
+ if(_buf_sz>0&&_buf==NULL)return OP_EFAULT;
+ _pic->type=picture_type;
+ _pic->width=width;
+ _pic->height=height;
+ _pic->depth=depth;
+ _pic->colors=colors;
+ _pic->data_length=data_length;
+ _pic->data=_buf;
+ _pic->format=format;
+ return 0;
+}
+
+int opus_picture_tag_parse(OpusPictureTag *_pic,const char *_tag){+ OpusPictureTag pic;
+ unsigned char *buf;
+ size_t base64_sz;
+ size_t buf_sz;
+ size_t tag_length;
+ int ret;
+ if(op_strncasecmp(_tag,"METADATA_BLOCK_PICTURE=",23)==0)_tag+=23;
+ /*Figure out how much BASE64-encoded data we have.*/
+ tag_length=strlen(_tag);
+ if(tag_length&3)return OP_ENOTFORMAT;
+ base64_sz=tag_length>>2;
+ buf_sz=3*base64_sz;
+ if(buf_sz<32)return OP_ENOTFORMAT;
+ if(_tag[tag_length-1]=='=')buf_sz--;
+ if(_tag[tag_length-2]=='=')buf_sz--;
+ if(buf_sz<32)return OP_ENOTFORMAT;
+ /*Allocate an extra byte to allow appending a terminating NUL to URL data.*/
+ buf=(unsigned char *)_ogg_malloc(sizeof(*buf)*(buf_sz+1));
+ if(buf==NULL)return OP_EFAULT;
+ opus_picture_tag_init(&pic);
+ ret=opus_picture_tag_parse_impl(&pic,_tag,buf,buf_sz,base64_sz);
+ if(ret<0){+ opus_picture_tag_clear(&pic);
+ _ogg_free(buf);
+ }
+ else *_pic=*&pic;
+ return ret;
+}
+
+void opus_picture_tag_init(OpusPictureTag *_pic){+ memset(_pic,0,sizeof(*_pic));
+}
+
+void opus_picture_tag_clear(OpusPictureTag *_pic){+ _ogg_free(_pic->description);
+ _ogg_free(_pic->mime_type);
+ _ogg_free(_pic->data);
}