JPG,GIF,MP3 to BMP, WAV

[necros]

am i right that converting to these formats means it`s lossless? (from compressed opened jpg to say just saving it with MSpaint into BMP)?

[SvenBent]

yes but you still inherit the flaws from the previous lossy encoding, so you dont get any quality benefits.
One small exception would be transparency info in .gif as I don't think bmp supports it.

What is the purpose of this ?

example when you do an abx of mp3 vs original the mp3 is very often decompresse back to .wav(PCM) format so you are ABX between two .wav files. this .wave file outputs the exact same data as the .mp3 files ( save for faulty players)

[m^3]

yes but you still inherit the flaws from the previous lossy encoding, so you dont get any quality benefits.
One small exception would be transparency info in .gif as I don't think bmp supports it.

What is the purpose of this ?

example when you do an abx of mp3 vs original the mp3 is very often decompresse back to .wav(PCM) format so you are ABX between two .wav files. this .wave file outputs the exact same data as the .mp3 files ( save for faulty players)

Do you know MP3 bitstream enough to tell with full certainity? I ask because I suspect there might be some accuracy loss when convertion frequency-domain floats to time-domain ints. Even though players do the conversion too, there may be information in the file that gets lost in the process and thus conversion would introduce further loss.

[necros]

thought maybe it`s a way to convert jpgs to like fliff, webp - with lossless options? not every compressor supports jpgs as input so question arose

[Jaff]

Any decompressed (optimised) JPG will always give a bigger output size when recompressed in any lossless way. Same thing applies to MP3's too.
What's the benefit in decompressing 1MB JPEG to 25MB and compress it lossless to 20MB?

[necros]

Ok i get it, no possible jpgs file size reduction converting losslessly to other formats.

[SvenBent]

Do you know MP3 bitstream enough to tell with full certainity? I ask because I suspect there might be some accuracy loss when convertion frequency-domain floats to time-domain ints. Even though players do the conversion too, there may be information in the file that gets lost in the process and thus conversion would introduce further loss.

Ofcause i DO...absolutely not
Not saying what you are saying a wrong I'm just having a hard time picturing any info beeing there in any audible matter that would be different since we basically have to convert it back to pcm to hear it. off cause there can always be decoder choices and flaws in the decoding step.
but a lot wiser men than me would know that.

[nemoW]

Ok i get it, no possible jpgs file size reduction converting losslessly to other formats.

Well, some high quality JPEGs of vector images and texts can be losslessly converted to PNG with possible size redictuion.

[thorfdbg]

Well, some high quality JPEGs of vector images and texts can be losslessly converted to PNG with possible size redictuion.

And they can be converted to even smaller JPEGs without loosing visual quality as well... (-;