Visualizza wikitesto di Convertire un file WAV in formato OggVorbis con le funzioni esterne del API di libvorbisfile, libvorbisenc e libogg

Per convertire un file "WAV" (ma anche un file "AIFF") in formato ''VorbisOgg'', è possibile utilizzare le risorse delle funzioni esterne contenute nelle librerie ''libvorbisfile'', ''libvorbisenc'' e ''libogg''.

Per poter fuire in Gambas di tali librerie esterne, è necessario avere installate le seguenti librerie condivise: "''libvorbisfile.so.3.3.8'' ", "''libvorbisenc.so.2.0.12'' " e "''libogg.so.0.8.5'' " .

Nel semplice esempio appresso mostrato, saremo costretti a creare, inoltre, un nostra apposita libreria dinamica condivisa esterna, nella quale porre una buona parte del codice necessario per la conversione, atteso che in Gambas attualmente non è dichiarabile un tipo di valore corrispondente al "''signed char'' ", come richiesto appunto dalla parte di codice C.
<BR>Il file WAV da convertire dovrà avere le seguenti caratteristiche fondamentali: 44100 hertz, 16 bit, 2 canali.
 Public Struct ogg_stream_state
   body_data As Pointer
   body_storage As Long
   body_fill As Long
   body_returned As Long
   lacing_vals As Pointer
   granule_vals As Pointer
   lacing_storage As Long
   lacing_fill As Long
   lacing_packet As Long
   lacing_returned As Long
   header[282] As Byte
   header_fill As Integer
   e_o_s As Integer
   b_o_s As Integer
   serialno As Long
   pageno As Long
   packetno As Long
   granulepos As Long
 End Struct
 
 Public Struct ogg_page
   header As Pointer
   header_len As Long
   body As Pointer
   body_len As Long
 End Struct
 
 Public Struct ogg_packet
   packet As Pointer
   bytes As Long
   b_o_s As Long
   e_o_s As Long
   granulepos As Long
   packetno As Long
 End Struct
 
 Public Struct vorbis_info
   version As Integer
   channels As Integer
   rate As Long
   bitrate_upper As Long
   bitrate_nominal As Long
   bitrate_lower As Long
   bitrate_window As Long
   codec_setup As Pointer
 End Struct
 
 Public Struct vorbis_comment
   user_comments As Pointer
   comment_lengths As Pointer
   comments As Integer
   vendor As Pointer
 End Struct
 
 Public Struct vorbis_dsp_state
   analysisp As Integer
   vi As Pointer
   pcm As Pointer
   pcmret As Pointer
   pcm_storage As Integer
   pcm_current As Integer
   pcm_returned As Integer
   preextrapolate As Integer
   eofflag As Integer
   lW As Long
   W As Long
   nW As Long
   centerW As Long
   granulepos As Long
   sequence As Long
   glue_bits As Long
   time_bits As Long
   floor_bits As Long
   res_bits As Long
 End Struct
 
 Public Struct oggpack_buffer
   endbyte As Long
   endbit As Integer
   buffer As Pointer
   ptr As Pointer
   storage As Long
 End Struct
 
 Public Struct vorbis_block
   pcm As Pointer
   opb As Struct Oggpack_buffer
   lW As Long
   W As Long
   nW As Long
   pcmend As Integer
   mode As Integer
   eofflag As Integer
   granulepos As Long
   sequence As Long
   vd As Pointer
   localstore As Pointer
   localtop As Long
   localalloc As Long
   totaluse As Long
   reap As Pointer
   glue_bits As Long
   time_bits As Long
   floor_bits As Long
   res_bits As Long
   internal As Pointer
 End Struct
 
 
 Library "<FONT Color=blue>libvorbisfile:3.3.8</font>"
  
 <FONT Color=gray>' ''void vorbis_info_init(vorbis_info *vi)''
 ' ''Initializes a vorbis_info structure and allocates its internal storage.''</font>
 Private Extern vorbis_info_init(vo_inf As Vorbis_info)
 
 <FONT Color=gray>' ''void vorbis_comment_init(vorbis_comment *vc)''
 ' ''Initializes a vorbis_comment structure for use.''</font>
 Private Extern vorbis_comment_init(vc As Vorbis_comment)
 
 <FONT Color=gray>' ''void vorbis_comment_add_tag(vorbis_comment *vc, const char *tag, const char *contents)''
 ' ''Adds a tag-comment pair to a vorbis_comment structure.''</font>
 Private Extern vorbis_comment_add_tag(vc As Vorbis_comment, tag As String, contents As String)
 
 <FONT Color=gray>' ''int vorbis_analysis_init(vorbis_dsp_state *v,vorbis_info *vi)''
 ' ''Allocates and initializes the encoder's analysis state inside a is vorbis_dsp_state.''</font>
 Private Extern vorbis_analysis_init(v As Vorbis_dsp_state, vi As Vorbis_info) As Integer
 
 <FONT Color=gray>' ''int vorbis_block_init(vorbis_dsp_state *v, vorbis_block *vb)''
 ' ''Initializes a vorbis_block structure and allocates its internal storage.''</font>
 Private Extern vorbis_block_init(v As Vorbis_dsp_state, vb As Vorbis_block) As Integer
 
 <FONT Color=gray>' ''int vorbis_analysis_headerout(vorbis_dsp_state *v, vorbis_comment *vc, ogg_packet *op, ogg_packet *op_comm, ogg_packet *op_code)''
 ' ''Creates and returns the three header packets needed to configure a decoder to accept compressed data.''</font>
 Private Extern vorbis_analysis_headerout(v As Vorbis_dsp_state, vc As Vorbis_comment, op As Ogg_packet, op_comm As Ogg_packet, op_code As Ogg_packet) As Integer
 
 <FONT Color=gray>' ''int vorbis_block_clear(vorbis_block *vb)''
 ' ''Frees the internal storage for a vorbis_block structure.''</font>
 Private Extern vorbis_block_clear(vb As Vorbis_block)
 
 <FONT Color=gray>' ''void vorbis_dsp_clear(vorbis_dsp_state *v)''
 ' ''Frees the internal storage for a vorbis_dsp_state structure.''</font>
 Private Extern vorbis_dsp_clear(vd As Vorbis_dsp_state)
 
 <FONT Color=gray>' ''void vorbis_comment_clear(vorbis_comment *vc)''
 ' ''Frees the internal storage associated with a vorbis_comment structure.''</font>
 Private Extern vorbis_comment_clear(vc As Vorbis_comment)
 
 <FONT Color=gray>' ''vorbis_info_clear(vorbis_info *vi)''
 ' ''Frees the internal storage for a vorbis_info structure.''</font>
 Private Extern vorbis_info_clear(vi As Vorbis_info)
 
 
 Library "<FONT Color=red>libvorbisenc:2.0.12</font>"
 
 <FONT Color=gray>' ''int vorbis_encode_init_vbr(vorbis_info *vi, long channels, long rate, float base_quality)''
 ' ''For setting up variable bitrate ("quality" based) modes.''</font>
 Private Extern vorbis_encode_init_vbr(vi As Vorbis_info, channels As Long, rate As Long, base_quality As Single) As Integer
 
 
 Library "<FONT Color=darkorange>libogg:0.8.5</font>"
 
 <FONT Color=gray>' ''int ogg_stream_init(ogg_stream_state *os,int serialno)''
 ' ''Initialize an ogg_stream_state struct and allocates appropriate memory in preparation for encoding or decoding.''</font>
 Private Extern ogg_stream_init(os As Ogg_stream_state, serialno As Integer) As Integer
 
 <FONT Color=gray>' ''int ogg_stream_packetin(ogg_stream_state *os, ogg_packet *op)''
 ' Submits a packet to the bitstream for page encapsulation.''</font>
 Private Extern ogg_stream_packetin(os As Ogg_stream_state, op As Ogg_packet) As Integer
 
 <FONT Color=gray>' ''int ogg_stream_flush(ogg_stream_state *os, ogg_page *og)''
 ' checks for remaining packets inside the stream and forces remaining packets into a page, regardless of the size of the page.''</font>
 Private Extern ogg_stream_flush(os As Ogg_stream_state, og As Ogg_page) As Integer
 
 <FONT Color=gray>' ''int ogg_stream_clear(ogg_stream_state *os)''
 ' ''Clears and frees the internal memory used by the ogg_stream_state struct, but does not free the structure itself.''</font>
 Private Extern ogg_stream_clear(os As Ogg_stream_state)
 
 
 Library "libc:6"
 
 <FONT Color=gray>' ''FILE *fopen(const char *__restrict __filename, const char *__restrict __modes)''
 ' ''Apre il file path associandolo ad uno stream.''</font>
 Private Extern fopen(__filename As String, modes As String) As Pointer
 
 <FONT Color=gray>' ''size_t fwrite(const void *__restrict __ptr, size_t __size, size_t __n, FILE *__restrict __s)''
 ' ''Scrive su stream nmemb elementi, ciascuno di dimensione size.''</font>
 Private Extern fwrite(__ptr As Pointer, __size As Integer, __n As Integer, __s As Pointer) As Integer
 
 <FONT Color=gray>' ''int fclose(FILE *__stream)''
 ' ''Chiude il file associato a stream.''</font>
 Private Extern fclose(stmP As Pointer) As Integer
 
 
 Library "/tmp/libso"
 
 <FONT Color=gray>' ''int creaOGG(FILE **fl, signed char readbuffer[READ*4+44], vorbis_info *vi, vorbis_comment *vc, vorbis_dsp_state *vd, vorbis_block *vb, ogg_stream_state *os, ogg_page *og)''
 ' ''Funzione contenente il codice in C puro per la creazione del file OGG.''</font>
 Private Extern creaOGG(inout As Pointer[], buff As Byte[], vi As Vorbis_info, vc As Vorbis_comment, vd As Vorbis_dsp_state, vb As Vorbis_block, os As Ogg_stream_state, og As Ogg_page) As Integer
 
 
 Public Sub Main()
  
  Dim percorsoFileWAV, percorsoFileOGG As String
  Dim readbuffer As Short[]
  Dim files As New Pointer[]
  Dim os As New Ogg_stream_state
  Dim og As New Ogg_page
  Dim vi As New Vorbis_info
  Dim vc As New Vorbis_comment
  Dim vd As New Vorbis_dsp_state
  Dim vb As New Vorbis_block
  Dim eos, ret, result As Integer
  Dim header, header_comm, header_code As New Ogg_packet
   
  Creaso()
   
  percorsoFileWAV = "<FONT Color=darkgreen>''/percorso/del/file.wav''</font>"
  percorsoFileOGG = "/tmp/audioOGG.ogg"
   
  readbuffer = New Byte[](1024 * 8 + 44)
   
 <FONT Color=gray>' ''Apriamo un file wav presumendo che sia 44.100 hertz, stereo, 16 bit:''</font>
  files.Push(fopen(percorsoFileWAV, "rb"))
  files.Push(fopen(percorsoFileOGG, "wb"))
    
  vorbis_info_init(vi)
   
  ret = vorbis_encode_init_vbr(vi, 2, 44100, 0.1)
  If ret <> 0 Then Error.Raise("Errore alla funzione 'vorbis_encode_init_vbr()' !")
   
 <FONT Color=gray>' ''Viene aggiunto un commento nel futuro file "ogg":''</font>
  vorbis_comment_init(vc)
  vorbis_comment_add_tag(vc, "ENCODER", "codificatore gambas")
   
 <FONT Color=gray>' ''Imposta lo stato di analisi e l'archiviazione ausiliaria di codifica:''</font>
  vorbis_analysis_init(vd, vi)
  vorbis_block_init(vd, vb)
   
  Randomize CInt(Time(Null))
  ogg_stream_init(os, Rnd())
   
  vorbis_analysis_headerout(vd, vc, header, header_comm, header_code)
   
  ogg_stream_packetin(os, header)
  ogg_stream_packetin(os, header_comm)
  ogg_stream_packetin(os, header_code)
 
  Write "\e[5mAttendere...\e[0m"
  Flush
 
 <FONT Color=gray>' ''In questo modo i dati audio effettivi avranno inizio su una nuova pagina, come da specifiche:''</font>
  While Not eos
    result = ogg_stream_flush(os, og)
    If result = 0 Then Break
    fwrite(og.header, 1, og.header_len, files[1])
    fwrite(og.body, 1, og.body_len, files[1])
  Wend
   
  creaOGG(files, readbuffer, vi, vc, vd, vb, os, og)
   
  Write "\rConversione da WAV a OGG terminata !"
   
 <FONT Color=gray>' ''Va in chiusura liberando la memoria precedentemente allocata:''</font>
  fclose(files[0])
  fclose(files[1])
  ogg_stream_clear(os)
  vorbis_block_clear(vb)
  vorbis_dsp_clear(vd)
  vorbis_comment_clear(vc)
 <FONT Color=gray>' ''La funzione "vorbis_info_clear()" va sempre chiamata per ultima:''</font>
  vorbis_info_clear(vi)
   
 End
 
 
 Private Procedure Creaso()
  
  File.Save("/tmp/libso.c", "/********************************************************************\n" &
                            "* THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *\n" &
                            "* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *\n" &
                            "* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *\n" &
                            "* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *\n" &
                            "* THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2007             *\n" &
                            "* by the Xiph.Org Foundation http&#058;//www.xiph.org/                  *\n" &
                            "********************************************************************/\n\n" &
  "#include <stdio.h>\n#include <vorbis/vorbisenc.h>\n#include <vorbis/codec.h>\n#include <ogg/ogg.h>\n\n" &
  "#define READ 1024\n\n" &
  "int creaOGG(FILE **fl, signed char readbuffer[READ*4+44], vorbis_info *vi, vorbis_comment *vc, vorbis_dsp_state *vd, vorbis_block *vb, ogg_stream_state *os, ogg_page *og) {\n\n" &
  "   ogg_packet op;\n" &
  "   int eos = 0, i;\n" &
  "   fseek(*fl, 4, SEEK_SET);\n\n" &
  "   while(!eos){\n" &
  "      long bytes=fread(readbuffer, 1, READ*4, *fl);\n\n" &
  "      if(0==bytes){\n" &
  "         vorbis_analysis_wrote(vd, 0);\n" &
  "      }else{\n" &
  "         float **buffer=vorbis_analysis_buffer(vd, READ);\n\n"
  "         for(i=0;i<bytes/4;i++){\n" &
  "            buffer[0][i]=((readbuffer[i*4+1]<<8) | (0x00ff&(int)readbuffer[i*4]))/32768.f;\n"
  "            buffer[1][i]=((readbuffer[i*4+3]<<8) | (0x00ff&(int)readbuffer[i*4+2]))/32768.f;\n}\n\n" &
  "         vorbis_analysis_wrote(vd,i);\n}\n\n" &
  "      while(vorbis_analysis_blockout(vd, vb)==1){\n\n" &
  "         vorbis_analysis(vb,NULL);\n" &
  "         vorbis_bitrate_addblock(vb);\n\n" &
  "         while(vorbis_bitrate_flushpacket(vd, &op)){\n\n" &
  "            ogg_stream_packetin(os, &op);\n\n" &
  "            while(!eos){\n" &
  "               int result=ogg_stream_pageout(os, og);\n" &
  "               if(0==result)break;\n" &
  "               fwrite(og->header,1,og->header_len,*(fl+1));\n" &
  "               fwrite(og->body,1,og->body_len,*(fl+1));\n" &
  "               if(ogg_page_eos(og)) eos=1;\n\n}\n}\n}\n}\n\n" &
  "               return (0);\n\n}")
  
  Shell "gcc -o /tmp/libso.so /tmp/libso.c -shared -fPIC -lvorbis" Wait
  
 End



=Riferimenti=
* https://xiph.org/vorbis/doc/
* https://xiph.org/ogg/doc/