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Topic: lossless cutters for lossy formats. (Read 1084 times) previous topic - next topic
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lossless cutters for lossy formats.

I'm looking for a good lossless cutter with suppor for the popular lossy audio codecs, mainly Opus, Vorbis, and AAC.
MP3 is well covered by the excelent mp3DirectCut, which marks the standard I'm after, with it's nice visual editor.

So far I've been using LosslessCut https://github.com/mifi/lossless-cut/, which does the job, at least in the technical aspect: That is, it cuts the file correctly as far as I can tell. The problem is that the interface is terrible for cutting audio.
The GUI is really meant for video, and, while, being based on FFmpeg, it also supports audio-only files, the position granularity seems to be meant for framesteps, which is not too good for audio. When fed with audio-only, it seems to assume a 60Hz framerate judging by to the rounded up 0.016666~ second steps that it allows. Interestingly, if you click in the positionbar, you may reach a postion that's not aligned to these imaginary frame boundaries, and if you use the framestep buttons from that non-aligned position, it advances the equivalent of 1 frame from that position. I assume that, with a video file, it will maintain frame boundary alignment, but I'm not editing video.
Specially aggravating is the fact that you are given a milisecond based timestamp but you can't manually edit those. You have to use the positionbar and the framestep buttons for everything.

Resuming, I'm looking for a good lossless cutter for these formats, hopefuly one that will approach the quality of mp3DirectCut.

Re: lossless cutters for lossy formats.

Reply #1
AAC is also covered by MP3DirectCut. Apparently, it can demux MP4 automatically with ffmpeg. I've never used that part of the program, and instead of having another copy of ffmpeg on the system, I prefer to use FAAD or MP4Box with another GUI. MP4Box or MP4Creator can also make MP4s if needed.

I'd like to see a visual cutter for DTS and AC-3 myself (for movies and concerts), which are much simpler formats.

Isn't 60 fps enough granularity given that audio formats offer 38-46 fps?

Re: lossless cutters for lossy formats.

Reply #2
AAC is also covered by MP3DirectCut. Apparently, it can demux MP4 automatically with ffmpeg.
I tried to drag an m4a file into it and it didn't complain, but neither did it do anything with it.
It DID complain about Opus not being supported when I tried to drop one, though.

Isn't 60 fps enough granularity given that audio formats offer 38-46 fps?
The main problem is the lack of any visual cue about the content of the file. The part where you can't directly specify cutpoints despite the program giving you the position down to miliseconds and you have to accept random granularity that has no basis on the underlying file just bothers me.
The program obviously has to round the actual cut point to a frame boundary, but you have zero control over that and instead are forced to juggle about with random 16.66666~ms steps counting from the last random point you managed to land on by clicking on the position bar... it annoys me quite a bit, especially considering how satisfying mp3DirectCut is in that regard.
The closest to any sanity is that the cursor keys allow for full 1s steps, but, of course, it's still just an offset from the current position, so you have to go back to the start of the file and advance from there second by second until your reach the desired full-second aligned cutpoint.

What's the point in having milisecond granularity if you have no control over it? It's just there, teasing you xD
It'd be something if the 60fps granularity was an absolute alignment from the start of the file. But it's just an arbitrary jump from an also arbitrary current position that you have no control over, either. Cutting audio like that is crude, feels random, and annoys me to no end.
But, again, it seems to be made with video in mind, and it seems to be just a happy coincidence that it can edit audio-only files too.

Re: lossless cutters for lossy formats.

Reply #3
For MP4 to be supported in Mp3DirectCut, you need ffmpeg.exe in the path or program directory, and type "ffmpeg.exe" in Configuration / Decoder / External demuxing. This field is blank by default. You also need libfaad2.dll. The program saves ADTS AAC; gain/fade isn't available.

http://i.imgur.com/VT4wXn5.png

Re: lossless cutters for lossy formats.

Reply #4
I wrote script using ffmpeg that I posted in this thread for lossless cutting of Opus files. It may help you out. There's some other links in that thread to.

Re: lossless cutters for lossy formats.

Reply #5
ffmpeg can cut virtually all formats without transcoding, and there's no need to write scripts, it's fairly easy to begin with.

 

Re: lossless cutters for lossy formats.

Reply #6
Is a lossless cutter really necessary? Can anyone ABX the difference between a second generation file of the same bitrate?

Re: lossless cutters for lossy formats.

Reply #7
Is a lossless cutter really necessary? Can anyone ABX the difference between a second generation file of the same bitrate?

That is not the question asked. Also, there IS generation loss after every time you encode again, even at high bitrates. The codes tries to encode a file that has slight artifacts. To encode these artifacts you have to keep other sounds out, resulting in..... artifacts. You get a buildup of artifacts quite fast, even after one generation. If it is audible after one generation depends on the bitrate.

Many lossy codec's don't handle the artifacts the produce themselves very good. They are artifacts after all and there for a reason.

Re: lossless cutters for lossy formats.

Reply #8
Is a lossless cutter really necessary? Can anyone ABX the difference between a second generation file of the same bitrate?

That is not the question asked. Also, there IS generation loss after every time you encode again, even at high bitrates. The codes tries to encode a file that has slight artifacts. To encode these artifacts you have to keep other sounds out, resulting in..... artifacts. You get a buildup of artifacts quite fast, even after one generation. If it is audible after one generation depends on the bitrate.

Many lossy codec's don't handle the artifacts the produce themselves very good. They are artifacts after all and there for a reason.

Let’s see your ABX results.

Re: lossless cutters for lossy formats.

Reply #9
Let’s see your ABX results.

Why have you turned this completely away from the OP's topic? Your post was irrelevant to the topic anyway and over 2 weeks after the discussion ended and now you're asking someone to produce ABX results? If you want an answer that question, make a thread about your original question and carry on. This thread was asking about lossless cutters for lossy files, not whether someone can ABX a second generation lossy file from the original lossy file.

 
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