[FFmpeg-user] Is FLAC lossless for compression_level > 0?

[Mark Filipak]

On 08/06/2025 20.39, Jim DeLaHunt wrote:
> On 2025-06-08 16:17, Mark Filipak wrote:
> 
>> On 08/06/2025 17.06, Jim DeLaHunt wrote:
>>> On 2025-06-08 13:35, Mark Filipak wrote:
>>>
>>>> Is FLAC (Free Lossless Audio Codec) lossless for compression_level > 0?
>>>
>>> Yes, says the FLAC documentation[1]: it is "an audio format similar to MP3, but lossless, meaning 
>>> that audio is compressed in FLAC without any loss in quality."
>> …[elided]…
>>> FLAC's documentation of the FLAC stream format[2] says:
>>> …[elided]…
>>
>> I'm reading the so-called specification. It's vague. 
> 
> As I read it, [2] is not a so-called "specification", it is a so-called "overview". So called in the 
> page title, "Format overview". If you look further through the FLAC documentation, you will see that 
> for a "FLAC format specification" it refers to RFC 9639[3]. That is the document to check for 
> vagueness.

Yes, RFC 9639. That's the so-called specification. I read it. It's vague. Compared to MPEG's 
specifications, it's quite vague.