[Gambas-user] reading files
Gianluigi
bagonergi at ...626...
Thu Jul 20 11:56:56 CEST 2017
Right ... and a look here too [0]
Ciao :)
Gianluigi
[0] http://www.gambas-it.org/smf/index.php?topic=5794.msg41793#msg41793
2017-07-20 3:15 GMT+02:00 Shane <buster6seven at ...626...>:
> thanks tony sounds like just what i needed i will take a look
>
> cheers
>
>
>
> On 19/07/17 22:34, Tony Morehen wrote:
>
>> I've attached an archive containing the code I use to read v1 and v2 MP3
>> tags and other MP3 info including bitrates (fixed and VBR), sampling rates
>> and number of channels. v1 tags are pretty staightforward to read if you
>> don't try to read the structure directly, but by each element of the
>> structure at a time. Some tips:
>>
>> 1) Numeric elements (bytes, bytearrays, shorts, integers, longs) can be
>> read directly from the stream. ie (4 byte Integer) = Read #Stream As
>> Integer. Gambas can handle little endian/big endian issues.
>>
>> 2) Fixed length strings must be handled in a two stage process. First,
>> the required string length number of bytes is read into a byte array. This
>> byte array is then converted to a string. Sample code:
>>
>> Dim Bytes As New Byte[StringLength]
>> Bytes.Read(Stream)
>> FixedString = Bytes.ToString()
>>
>> Note: Bytes.ToString stops the string conversion at the first null or at
>> the end of the array. Therfore, you don't have to worry about
>> null-terminated strings.
>>
>> v2 tags are more complicated, particularly since the tags can be ascii,
>> either kind of utf16, or utf8 encoding. The code I sent has been tested
>> with over 10,000 mp3 files has seems to have no issues.
>>
>>
>> On 2017-07-19 12:33 AM, Shane wrote:
>>
>>> thank you Gian i did take a rest and read but alas it did not help
>>>
>>> as far as i see it he is saying don't use binary file for fixed length
>>> strings
>>>
>>> but as this is an mp3 file tag witch i have no control i am doomed
>>>
>>>
>>>
>>> On 18/07/17 19:22, Gianluigi wrote:
>>>
>>>> Why do not you take a moment of rest and read what Tobias Boege
>>>> recommend
>>>> me in the discussion [0] I told you here [1]?
>>>>
>>>> [0]
>>>> http://gambas.8142.n7.nabble.com/Random-access-files-with-fi
>>>> xed-length-string-td50880.html
>>>> [1] http://gambas.8142.n7.nabble.com/vb-code-td59764.html
>>>>
>>>> 2017-07-18 9:04 GMT+02:00 Shane <buster6seven at ...626...>:
>>>>
>>>> I am very confused from the docs
>>>>>
>>>>> _Variable_ *= READ* [ *#* _Stream_ ] *AS* _Datatype_
>>>>>
>>>>> _Variable_ *= READ* [ *#* _Stream_ *,* ] _Length_
>>>>>
>>>>> so wouldn't it be_
>>>>> _
>>>>>
>>>>> IDtag = read #hfile as ID3v1_TAG ?
>>>>>
>>>>> with doesn't work by the way
>>>>>
>>>>>
>>>>>
>>>>> On 18/07/17 12:44, nando_f at ...951... wrote:
>>>>>
>>>>> I think
>>>>>> Read #hfile, IDtag, ID3v1_TAG
>>>>>> should be
>>>>>> Read #hfile, IDtag as ID3v1_TAG
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Open WebMail Project (http://openwebmail.org)
>>>>>>
>>>>>>
>>>>>> ---------- Original Message -----------
>>>>>> From: Shane <buster6seven at ...626...>
>>>>>> To: gambas-user at lists.sourceforge.net
>>>>>> Sent: Tue, 18 Jul 2017 10:50:43 +1000
>>>>>> Subject: Re: [Gambas-user] reading files
>>>>>>
>>>>>> i don't know what i am doing wrong
>>>>>>
>>>>>>> Public Struct ID3v1_TAG '(128 bytes)
>>>>>>> Tag[3] As String 'always TAG
>>>>>>> Title[30] As String 'title, 30 characters
>>>>>>> Artist[30] As String 'artist, 30 characters
>>>>>>> Album[30] As String 'album, 30 characters
>>>>>>> Year[4] As String 'year, 4 characters
>>>>>>> Comment[30] As String 'comment, 30 characters (or
>>>>>>> 28 if
>>>>>>> track# included)
>>>>>>> Genre As Byte 'genre, 255 for none defined
>>>>>>> End Struct
>>>>>>>
>>>>>>> Private Sub GetID3v1(File As String)
>>>>>>> Dim IDtag As ID3v1_TAG
>>>>>>> Dim hfile As File
>>>>>>>
>>>>>>> hfile = Open File For Read
>>>>>>>
>>>>>>> '
>>>>>>> 'read the tag
>>>>>>> ' seek to end of less tag size
>>>>>>>
>>>>>>> Read #hfile, IDtag, ID3v1_TAG
>>>>>>>
>>>>>>> here i get IDtag is NULL
>>>>>>>
>>>>>>> On 18/07/17 05:05, nando_f at ...951... wrote:
>>>>>>>
>>>>>>> Yes it is possible, I do it. here is some code (incomplete)
>>>>>>>>
>>>>>>>> -Nando (Canada)
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> ' top of class file
>>>>>>>> Public Struct recstruc
>>>>>>>> _a as integer
>>>>>>>> _b as integer
>>>>>>>> _c as integer
>>>>>>>> end struct
>>>>>>>>
>>>>>>>>
>>>>>>>> ' a function
>>>>>>>> public function openAfile(filename as string) as file
>>>>>>>>
>>>>>>>> dim hfile as file
>>>>>>>> dim arec as recstruc
>>>>>>>>
>>>>>>>> hfile = open filename for read write create
>>>>>>>>
>>>>>>>> with arec 'some values to write.
>>>>>>>> ._a = 1
>>>>>>>> ._b = 22
>>>>>>>> ._c = 333
>>>>>>>> end with
>>>>>>>>
>>>>>>>> write #hfile, arec as recstruc
>>>>>>>>
>>>>>>>> 'if you position the hfile pointer back to zero, you can...
>>>>>>>> read #hfile, arec as recstruc
>>>>>>>>
>>>>>>>> close #hfile
>>>>>>>>
>>>>>>>> end
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Open WebMail Project (http://openwebmail.org)
>>>>>>>>
>>>>>>>>
>>>>>>>> ---------- Original Message -----------
>>>>>>>> From: T Lee Davidson <t.lee.davidson at ...626...>
>>>>>>>> To: gambas-user at lists.sourceforge.net
>>>>>>>> Sent: Sun, 16 Jul 2017 12:42:35 -0400
>>>>>>>> Subject: Re: [Gambas-user] reading files
>>>>>>>>
>>>>>>>> On 07/16/2017 06:57 AM, Shane wrote:
>>>>>>>>
>>>>>>>>> given this example
>>>>>>>>>>
>>>>>>>>>> PRIVATE SUB BinaryRead(FilePath AS String)
>>>>>>>>>> DIM binaryFile AS File
>>>>>>>>>> DIM i AS Integer
>>>>>>>>>> DIM b AS Byte
>>>>>>>>>> DIM s AS Short
>>>>>>>>>> DIM s1 AS String
>>>>>>>>>> DIM s2 AS String
>>>>>>>>>> ' Read binary file
>>>>>>>>>> binaryFile = OPEN FilePath FOR READ
>>>>>>>>>> READ #binaryFile, i
>>>>>>>>>> READ #binaryFile, b
>>>>>>>>>> READ #binaryFile, s
>>>>>>>>>> READ #binaryFile, s1
>>>>>>>>>> READ #binaryFile, s2
>>>>>>>>>> CLOSE #binaryFile
>>>>>>>>>> ' Display results
>>>>>>>>>> PRINT i
>>>>>>>>>> PRINT b
>>>>>>>>>> PRINT s
>>>>>>>>>> PRINT s1
>>>>>>>>>> PRINT s2
>>>>>>>>>> END
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> is there a way for gambas to read a struct of all these variables
>>>>>>>>>> in one read ?
>>>>>>>>>>
>>>>>>>>>> You may have hinted at the solution within your question. Have you
>>>>>>>>>>
>>>>>>>>> considered
>>>>>>>>> using a Structure?
>>>>>>>>>
>>>>>>>>> http://gambaswiki.org/wiki/lang/read :
>>>>>>>>> "... reads the stream Stream as binary data whose type is
>>>>>>>>> specified by
>>>>>>>>> the
>>>>>>>>> Datatype argument."
>>>>>>>>>
>>>>>>>>> "The returned datatype can be one of the following: NULL, Boolean,
>>>>>>>>> Byte, Short,
>>>>>>>>> Integer, Long, Pointer, Single, Float, Date, String, Variant,
>>>>>>>>> any
>>>>>>>>> Array,
>>>>>>>>> Collection or structure."
>>>>>>>>>
>>>>>>>>> http://gambaswiki.org/wiki/lang/structdecl
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Lee
>>>>>>>>>
>>>>>>>>> ------------------------------------------------------------
>>>>>>>>> ------------------
>>>>>>>>> Check out the vibrant tech community on one of the world's most
>>>>>>>>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
>>>>>>>>> _______________________________________________
>>>>>>>>> Gambas-user mailing list
>>>>>>>>> Gambas-user at lists.sourceforge.net
>>>>>>>>> https://lists.sourceforge.net/lists/listinfo/gambas-user
>>>>>>>>>
>>>>>>>>> ------- End of Original Message -------
>>>>>>>>
>>>>>>>>
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>>>>>>> ------- End of Original Message -------
>>>>>>
>>>>>>
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