Software to easily concatenate collections of mp3 files with the best quality and the smallest size, taking into account both the maximum required quality and the compatibility with the target player.
Uses the latest version of LAME, version 3.100, customly compiled to adapt to the in-use cpu, so that it can be used with cpus as old as the Pentium and Windows versions as old as Windows XP.
The program is profile based, to make it easier to use. Specifically, there are two main profiles, the Audiophile (bitrate 320kbps) and the on-the-go (bitrate 192kbps) ones, which are further subdivided in stereo or mono.
The encoding method for mp3 files can be chosen (abr, cbr, or vbr), so that one can choose whether to use the better encoding method in terms of both quality and file size (variable-bit-rate = vbr) or the most compatible one (constant-bit-rate = cbr).
As encoding audio into the mp3 format is a lossy operation, whenever possible the original audio is not re-encoded, being the stream corresponding to it just copied to the target file as is or with its frames re-formatted as required to be in accordance with the target format; when this happens, the process is lossless and, as so, does not use LAME but code specifically created for the purpose by the author of this program. The information regarding whether or not the audio on the original file has been (re-)encoded is shown on the information displayed by the program on its grid view.
Concatenating (the audio streams corresponding to) mp3 files is much more difficult than what might appear when you undertake a google search. Specifically, when you do such a search, you will be given plenty of results claiming that joining the audio on mp3 files can be undertaken simply by concatenating/joinning the contents of the source mp3 files into the target one. This is not correct and if you do this you will be asking for trouble, being some of the reasons for the problems that may arise the following:
1) mp3 files may have more information into them than the one corresponding to the mp3 stream (for instance, they may have tags) and a player is supposed to ignore such information after it has found and played the mp3 stream (if you concatenate an mp3 file to one that has a tag at the end, then only the mp3 stream corresponding to the first file will be found and played, as the player is supposed to ignore the information that comes after the mp3 stream it has played);
2) the number of channels specified by different mp3 files may not be equal, ones may be encoded in stereo and the other ones may be encoded in mono, thus the decoding process of the concatenated file may originate buffer problems if the decoder does not re-configure the process for each frame of the mp3 stream (which normally is the case, as it is much more efficient to consider that the whole stream is encoded in the same way), giving rise to parts of the music that do not sound like that;
3) the sampling frequency specified by different mp3 files may not be equal, thus the decoding process of the concatenated file may originate buffer problems if the decoder does not re-configure the process for each frame of the mp3 stream (which normally is the case, as it is much more efficient to consider that the whole stream is encoded in the same way), giving rise to parts of the music that do not sound like that; and
4) one mp3 file may use a free-format bitrate and at least one other uses a normal-format bitrate (or uses a free-format bitrate that is not equal to the other one), thus the decoding process of the concatenated file may originate buffer problems if the decoder does not re-configure the process for each frame of the mp3 stream (which normally is the case, as it is much more efficient to consider that the whole stream is encoded in the same way), giving rise to parts of the music that do not sound like that;
5) sometimes the ancillary-data corresponding to the last mp3 frame (on a mp3 stream) on a file is not included on the file, in order to save space, thus a fake one must be generated before joining mp3 streams or the following mp3 stream will not be found;
In order to avoid all the corner cases that may arise when trying to simply concatenate mp3 files, programs that do not understant the mp3 format will simply ask a mp3 encoder (like ffmpeg or lame) to re-encode the original audio stream into a new one, which is a lossy process, as explained before.
The Batch Mp3 Concatenator (as explained before) does not do this; it reads the mp3 stream on each file and tries to re-format it as needed (lossless process) and only when this is not possible it asks LAME to re-encode the audio corresponding to it (lossy process).
The program is batch-based, meaning that as soon as the settings are chosen they can be applied to as many files as you wish - you just have to let it process all of them.
Last but not least, the program does not require any installation - it is a portable one. Thus, it can be run from a pen drive.