Manpage of mpgedit
Section: User Commands (1)
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mpgedit - MPEG 1/2/2.5 audio (mp3) file editor
- mpgedit -h | -H | -V | [ -c [inputfile1 [inputfile2...]]]
mpgedit [-s] [-v[v[v[v[v]]]]] [-p] [-d N] [-e [start[-[end]]]] [-E] [-I] [-X[0|1|2]] [-L] [-l volume] [-f] input_file [-o [+]outfile_name ]
mpgedit [-D] [-DbN] [-DcN] [-DmN] [-Ds] [-d N] input_file [input_file2 ...]
mpgedit is an MPEG 1 layer 1/2/3, MPEG 2, and MPEG 2.5 audio (mp3)
file editor that is capable
of processing both Constant Bit Rate (CBR) and Variable Bit Rate (VBR) encoded
files. mpgedit can cut an input MPEG file into one or more output files, as
well as join one or more input MPEG files into a single output file. When
editing VBR files that have a XING header, mpgedit updates the output
file's XING header information to reflect the new file size and
average bit rate.
When editing a file, mpgedit locates the nearest MPEG frame boundary for the
desired start and end times, then copies the frames between these times
to the output file. Since no file decoding / encoding occurs during editing,
there is no audio quality loss when editing with mpgedit.
For each file being edited, a time index file is
created that stores the file position, in bytes, for every 1 second of
play time. Indexing guarantees correct and fast random access to
edit time offsets for VBR-encoded files.
mpgedit file playback allows
edit-time audio playback auditioning, which insures that desired cut occurs
at the correct time
offset. This feature is necessary when making edits that demand sub-second
accuracy (especially with VBR files). Since most MP3 players display
playback run times based on a VBR file's average encoded bit rate,
edits based on these players' displayed times can miss the desired
start or stop time by many seconds.
It is not necessary to use
the playback functionality to make edits when the edit start and stop
times are already known. The playback feature is merely an aid for
accurately locating the desired edit start and stop times.
mpgedit operates in two modes: a command line and a curses-based, full-screen
interactive shell. All editing functionality is available in both modes.
The chief advantage of the interactive mode comes when using the playback
feature for selection and verification of edit begin and end times,
which is more rapidly performed interactively.
COMMAND LINE OPTIONS
Command line mode has the following options available:
- -c [input file] [input file 2] ... [input file N]
Curses edit mode. Enter a full-screen, interactive editing session to
play back input files and set begin and end times for each edit. This
mode is the default action when no arguments are supplied.
- -d N
Specifies playback or decoding decimation level. When used with
playback, every Nth frame is played. When used with -D, the default
decimation level of 9 is replaced with the value specified. There is
a serious performance penalty for using a smaller decimation level
when decoding (-D option), and rarely is the increased silence
detection resolution required.
Decode input files and computes average volume for every decoded
frame. The amplitude values are stored in a file named input.lvl.
Once decoded, segment boundaries separated by a minimum amplitude
threshold are detected, storing the result of that analysis in the
file levels_session. The default decimation level used by this
operation is 9, or about 3 frames per second. This default is changed
with the -d option.
Same as -D, but override the SILENCE_THRESHOLD parameter. The default
value is 30, setting the silence threshold to -30db below the average
input file amplitude. Lower values detect segment boundaries
containing louder content. Valid values are 6-96.
Same as -D, but override the SILENCE_REPEAT parameter, the number
consecutive decoded samples below the silence threshold that must
occur before a segment boundary is detected. The default value is 3,
or about one second of silence when the default decimation level (-d
option) of 9 is used.
Same as -D, but override the MINIMUM_TIME parameter, the number of
seconds that must elapse once a segment boundary has been detected
before another boundary can be detected. The default value is 90
Decode the input file, writing the output to standard output.
- -e start[-[end]]
Perform copy/paste operation on input files. The input MP3
file may be encoded as either CBR or VBR. For quick and accurate
random access to VBR-encoded files, an external time index file
is created. The index file uses the basename of the input file
with the '.idx' extension.
The output files created by this option are located in the same
directory as the input MPEG file. When the input directory is
read-only, the output is written to the current working directory.
When the -o option is not used, the copy/paste data is
written to a file with the same basename as the input file with
the '_nn.mp3' extension, where nn is an integer value. When a
file named basename_nn.mp3 already exists, the integer nn is
incremented until the filename is unique. The input MPEG file is
never overwritten by this option.
When only a start time is specified, the copy/paste operation is
performed from that start time through the end of file. When just
an end time is specified, the copy/paste operation is performed
from the beginning of the file through the specified end time.
When both start and end times are specified, the portion of the
file bracketed by these times is copy/pasted. Start and end times
are specified in seconds, or MM:SS.mmm, where MM is minutes, SS
is seconds, and mmm are milliseconds. Although any millisecond
value may be specified, it will always be rounded off to the next
frame boundary, approximately 26ms.
Multiple -e options are allowed. Each -e represents a separate edit
that will be performed on the named input file. When multiple -f options
are present, the -e options immediately preceding each -f option apply to
that input file.
Suppress performing edit when -e option is used. Useful
when both -e and -v options are used to generate verbose output for a
portion of an input file, while performing the edit is not desired.
Suppress indexing operation prior to performing specified edit.
Depending on the situation, this feature may perform the desired
edit in less time in conjunction with indexing. One example is
cutting a portion of a file being captured in real time while it is
being encoded. In this situation, the growing size of the input
MP3 file will confuse the index generator. Warning: Seek performance
of the -I option is much slower than using an index file,
as all frames between the start of the file to the seek time are
- -f input file name
Use the named input file.
Multiple -f options are allowed. At least one -e option must be
precede each -f option.
If multiple input files are specified, all -e options in a group apply
to the -f immediately following a group of -e options. For example:
mpgedit -e 2-12 -f foo1 -e 20-30 -f foo2
-e 2-12 applies to foo1, -e 20-30 applies to foo2.
- -o output file
Use the named output file. Prefixing a + to filename causes output from
an edit to be appended
to the output file. XING headers are automatically updated when
using this option.
Display command line usage summary.
Display long help information. Detailed usage descriptions for each command line option are displayed.
- -l left[:right]
Set the current playback device volume level to a value between 0 and 100.
Specifying only a left value sets both left and right
channels to that value.
Display the current playback device volume level.
Play MPEG file using external player.
All of the normal informational messages are suppressed during
indexing and editing.
Verbose output. Adding another v increases verbosity.
Up to -vvvvv are allowed. -v displays the frame count and file
offset at one second increments. -vv adds the following information
for each frame: time offset, bitrate, frame size, frame count,
frame position. -vvv adds to -vv and displays a detailed
breakdown of each MPEG frame header. -vvvv adds an MD5 checksum
to the -vv output. -vvvvv adds an MD5 checksum to the
Display mpgedit version.
Manipulate XING header. -X0 omits the XING header prefix, allowing output
to be appended to the end of a previous edit. -X1 fixes the XING header
after catenating edits. These two options are largely obsolete because
mpgedit now properly updates the XING header when editing and concatenating
-X2 adds a XING header to a file missing this header,
then updates the XING statistics.
The -X1 modifies the input file's XING header in place. This is the
one exceptional case when mpgedit modifies the input file.
The -X2 option generates a new file, containing the XING header prefix,
followed by the contents of the input file. The output file is defaulted
when the -o outfile option is not used. The default output file name
is the same basename as the input file name, with the '_newxing_nn.mp3'
extension, where nn is a unique integer extension.
This example illustrates the addition of a XING header to a file without this
mpgedit -X2 myfile.mp3
This command generates the new file myfile_newxing_1.mp3,
containing a XING header prefix, followed by the contents of the
input file myfile.mp3
Note: Releases of mpgedit prior to 0.6p1 did not always
properly update the Xing header after performing an edit. Using mpgedit
0.6p1, or later, these incorrect headers can be fixed with the
mpgedit -X1 file_to_fix.mp3
Note: The addition of a XING header to a CBR file is possible with the
-X2 option. Although harmless, the addition of a XING header to
such a file is unnecessary, and redundant. However, when joining a
CBR file followed a VBR file, the addition of a XING header becomes
necessary in order for some MP3 players to properly display the
elapsed run time.
INTERACTIVE MODE COMMANDS
Interactive mode uses single key commands to control editing functionality.
Command key binding are similar to vi edit commands. Interactive mode
has the following edit commands available:
Same as j.
Same as h.
Same as l.
Same as k.
- k, Arrow_Up
Move the cursor up one line.
- j, Arrow_Down
Move the cursor down one line.
- l, space, Arrow_Right
Move the cursor right one field on the current line.
- h, Arrow_Left
Move the cursor left one field on the current line.
Toggle between start and end time fields.
Move the cursor home to the first line in the editor.
Move the cursor to the last line in the editor.
Undo any changes to the current line. All changes can be undone
until the cursor is moved to another line.
Decrease selected time field by one count.
Increase selected time field by one count.
For each of the start and end
time input fields, the minute, second, and millisecond values can be modified.
The desired numeric value can be directly input from the keyboard,
or the current value can be modified by incrementing or decrementing
the current value
up with the . command and down with the , command.
Enter autoedit mode. A configuration menu is first presented,
which allows setting
the input file name, and silence detection parameters,
After making any modifications to the configuration menu,
the input file is analyzed and silent periods are automatically
detected. The main edit window is populated with the start/stop
times for each segment separated by a silent period. See the
AUTOMATIC EDITING section for additional details about this feature.
Multiple input file names may be entered, separated by spaces or commas.
When a comma separator is used, spaces loose their separator meaning.
Use a comma separator makes entering multiple file names where
spaces are part of the file name more convenient. Preceding a space
character or a comma with a backslash (\) quotes that character,
and it is no longer interpreted as a separator. The file named
music,1.mp3 must be entered as music\,1.mp3, for example.
The file Styx - Mr. Roboto.mp3 must be entered as
Styx\ -\ Mr.\ Roboto.mp3 when the comma separator is not used,
as each space would be interpreted as a separator.
Clear editor. All currently specified edits are cleared. The user is
warned that unsaved changes will be lost before clearing the editor.
Clear currently selected start or end time. All three time components
(minutes, seconds and milliseconds) are reset to zero when the c command
is entered. Only the currently selected start or end field is
cleared with the c command.
Paste the previously deleted line above the cursor position.
Paste the previously deleted line below the cursor position.
Insert a new line above the cursor position.
Insert a new line below the cursor position.
Delete the line at the cursor position.
Join the edit time of the line below the cursor with the current line.
The end time of the current line is changed
to be the end time of the following line, then the
following line is deleted. Before this change is made, the current line
and the following line are yanked into the undo buffer.
Specify the output file to save all specified edits to. This name
must be specified before the e (perform edit) command will function.
Edit the input filename field. Entering a
^U (ctrl-U) key deletes all characters in the field. Entering a
Backspace key deletes only the previous character. Arrow_Left and
Arrow_Right positions the cursor within the name field. Characters are
added in insert mode, and will not over write following characters. ESC will
undo changes and exit the field.
Enter will accept the current value as the input filename.
The named input file will be indexed when the Enter key is pressed,
if the index file does not already exist.
Play the input file at the time specified in the currently selected
start or end time field. Playback will continue
until any key is pressed. Playback will pause when the Enter
key is pressed, and will resume with another Enter key press. During
playback, the current time offset is displayed at the bottom of the screen.
The chief advantage of the s command is the ability to
rapidly select a start or end time, begin and end playback,
modify the time, and play back again. By repeating these steps,
the precise time can be located.
Play the input file up to the time specified in the currently selected
start or end time field. Playback will begin at 5 seconds before the
selected time, and will stop at the selected time.
This feature is useful when searching for a break between two music
selections, where the previous piece ends loudly and the next
piece begins softly. Playing back a few seconds before the edit end time
enables precisely locating breaks between pieces of music.
Load edit files and times from a previous mpgedit session. All edit
file names and times are saved when exiting an interactive session with
the e, E and q commands. The L command loads
these saved edit specifications
for subsequent modification.
Quit all edits and discard changes. All work performed during the
current interactive session is discarded with this command, so use it
Quit an interactive edit session and save the current edit files and times.
This saved information can be loaded with the L command to resume
the edit session at a later time.
None of the MPEG file edits occur when using this command. mpgedit
prompts for the name of the file to save the edit specifications to.
When this file already exists, mpgedit prompts for whether
to over write the file.
To save to a different file answer no, then q again and modify the
Perform MPEG file edits using current input file and time specifications.
The edits are saved to the output filename specified by the last n
command. An output name must be specified with n before e
will perform any edits. All input file names and edit times are saved,
as with the q command, before the MPEG file edits are performed.
Perform MPEG file edits using current input file and time specifications.
The edits are saved to default output filenames. The default
output filenames are
the same basename as the input file, with the '_nn.mp3' extension
appended, where nn is a unique integer value.
All input file names and edit times are saved,
as with the q command, before the MPEG file edits are performed.
- v, V
Adjust the current playback device volume level. v reduces the
volume level by two settings;
V increases the volume level by two settings. The allowed
volume range is between 0 and 100.
mpgedit can edit a file automatically by searching for periods of
silence in an input file. Each silent period found represents
an edit that will be performed on the input file. The results of this
editing analysis are stored in a saved session file named
levels_session. This session file can be loaded for review in an
mpgedit interactive curses session (see the L interactive mode
command) or by xmpgedit (see the Load Session... section
described in xmpgedit(1)). Specifying both the -D and -c
command line options will load the automatic edits into an mpgedit
interactive curses session. Automatic edit mode can be entered in an
interactive curses session with the A command.
mpgedit automatic editing requires each input file be decoded
into its PCM or .wav representation. This decoding is done only
purposes of silence detection. Once the edit times for each silence boundary
have been detected, all edits are performed on the original input files without
decoding or re-encoding. The results of the input file decoding are stored
in a corresponding input.lvl file. The .lvl file stores the
average volume level for representative frames from the input file.
By default, every 9th frame from the input file is decoded, corresponding
to approximately 3 volume samples per second. This default may be changed
by the -d N option. This skipping of frames is done for performance
reasons, since decoding MP3 data to its PCM representation is a
computationally expensive operation. For most applications, 3
audio samples per second is sufficient to accurately detect silence boundaries.
This is simplest automatic editing example:
mpgedit -D input.mp3
These operations are performed by this command:
Create the index file input.idx when it does not already exist.
Create the decoded audio levels file input.lvl.
Search for periods of silent present in input.lvl, then store
corresponding edits in the levels_session file.
After this analysis is complete, load the levels_session file
into mpgedit for review and further refinement of the edit start and
Sometimes it is necessary to override one or more of the parameters controlling
silence detection. The mpgedit default values generally work
for all content, but sometimes it is necessary to tweak these parameters
to obtain the desired results.
mpgedit -Dm30 -Db20 input.mp3
This example reduces to 30 seconds the amount of time that must pass
before a subsequent segment boundary can be detected. The silence threshold
has also been reduced to -20db, allowing louder sections to be detected
as a segment boundary.
A space character must not appear between any character in the
-DbN, -DcN, or -DmN, options.
Creation of the input.lvl file may take a very long time, possibly
several minutes depending on the length of the input file and the
CPU speed of the computer running mpgedit.
Once the input.lvl file has been created, subsequent silence
detection passes will run much faster, usually less than a second, depending
on the length of the input file.
These parameters control the silence detection analysis, modifying
the sensitivity of the detection.
- SILENCE_THRESHOLD (-DbN) Default value: 30
This parameter specifies how many decibels below the average audio level of
entire input file an audio sample must fall before it is considered "silent".
The larger the value of this
parameter, the quieter an audio sample must be to qualify as an edit boundary.
The valid range of this parameter is between 6 and 96.
- SILENCE_REPEAT (-DcN) Default value: 3
Controls the number of consecutive audio samples quieter than the
SILENCE_THRESHOLD that must occur
before an edit boundary is detected. The default value is 3, which
corresponds to about 1 second of silence when the default decoding
decimation (see the -d N option) of 9 is used. Larger
SILENCE_REPEAT values reduce the risk of false positive segment boundary
detection. However, too large a value for SILENCE_REPEAT
also increases the risk a segment boundary will not be properly detected.
- MINIMUM_TIME (-DmN) Default value: 90
This parameter specifies how many seconds must elapse since the last
segment boundary has been detected before another segment boundary can be
detected. This parameter is
useful for reducing the occurrence of segment boundary false positive detection.
Choosing the proper value for this parameter is content dependent. For
example, some music contains frequent periods of silence. Sections
of silence that occur before the MINIMUM_TIME has expired will be
contained within an edit segment, instead of defining a new edit boundary.
However, there will always be cases where
it is impossible to determine if a period of silence should divide two
segments, or should be contained within a segment.
- mpgedit -Dm30 -Db36 -c radiomusic.mp3
Automatically edit the input file radiomusic.mp3. Using -c loads
the results of the silence detection analysis into an mpgedit
interactive curses session, where the segment start/stop times may be
reviewed for correctness in the interactive session before performing the
edits on the input file.
The MINIMUM_TIME (-Dm30) parameter is set to 30 seconds,
and the SILENCE_THRESHOLD (-Db36) parameter is lowered to 36
decibels in this example.
- mpgedit -e-6.500 -e6.500-12.500 -e12.500-19 -e19- test1.mp3
Cut the file test1.mp3 into 4 pieces. The first cut starts at
the beginning of test1.mp3, and ends at 6 1/2 seconds; cut 2 begins at
6 1/2 seconds, and ends at 12 1/2 seconds; cut 3 begins at 12 1/2 seconds
and ends at 19 seconds; cut 4 begins at 19 seconds and includes the
remainder of test1.mp3.
- mpgedit -o output.mp3 -e- test1_1.mp3 test1_2.mp3 test1_3.mp3 test1_4.mp3
Join four MP3 files together into a single output file. The edit time
specification -e- means start from the beginning of the file
and run through to the end of the file. In this example, only one edit
time specification is needed, and is applied to all input file names
that follow. Note the -f option can be omitted when the remainder
of the command line is input file names.
- mpgedit -e19- -f output.mp3 -e-6.500 -f test1.mp3
This example joins cuts from two different files. The first cut
is from output.mp3, start at 19 seconds and ending at the end of
file. The second is from from test1.mp3, starting at the
beginning of the file and ending at 6 1/2 seconds. The default
output filename is used (output_1.mp3). The cuts from both input
files are stored in output_1.mp3 because the first cut ends at
the end of file and the second cut starts at the beginning of
- mpgedit -e-6.500 -e12.500-19 -f test1.mp3 -e2.500-6 -f test2.mp3
Create 3 cuts, two from test1.mp3, one from test2.mp3. In this
case, the default output file names are created, resulting in the
three cuts stored in test1_1.mp3, test1_2.mp3, and test2_1.mp3,
- mpgedit -o edits.mp3 -e-6.500 -e12.500-19 -f test1.mp3 -e2.500-6 -f test2.mp3
Performs the same edits as the previous example, but saves the edit results in
one output file, named edits.mp3.
- mpgedit -e19- -p test1.mp3
Begin sound playback from the file song1.mp3 beginning
19 seconds into the file.
- mpgedit -vvv elgar.mp3
Parse MPEG audio file frames, and display frame information. This example
demonstrates the output displayed when -vvv is used. For the purposes
of this discussion, lines tagged with (1), (2) and (3) correspond to -v, -vv
and -vvv respectively; the (1), (2) and (3) do not appear in the actual output.
Found xing header
h_id = 1
h_layer = 3
h_protect = 0
samprate = 44100
flags = 15
frames = 18146
bytes = 9238103
vbr_scale = 44
(1) *** t=1s fr=39 pos=22232 (0x56d8)
(2) MPEG header t=1.044s br=192 sz=626 fr=40 pos=22232 pos=0x56d8
(3) File position: 0 (0x0)
(3) Frame size: 626 (0x272)
(3) MPEG version: 3 (MPEG Version 1)
(3) MPEG layer: 1 (Layer III)
(3) Protection: 0 (no)
(3) bitrate: 11 (192)
(3) sample_rate: 0 (44100)
(3) Pad: 0 (no)
(3) Private: 0 (no)
(3) channel_mode: 1 (Joint stereo)
(3) joint_ext_mode: 0 (Intensity stereo off; Mid-side stereo off)
(3) Copyright: 0 (no)
(3) Original: 1 (yes)
(3) Emphasis: 0 (None)
File name: elgar.mp3
VBR Min: 80
VBR Max: 192
VBR Average: 150
Total frames: 15584
File size: 7623958
Track length: 6:47.85 (407s)
Variable Bit Rate frame statistics
Bit Rate Frame Count
80 kbps: 1 (<1%)
96 kbps: 27 (<1%)
112 kbps: 733 (4%)
128 kbps: 4169 (26%)
160 kbps: 10196 (65%)
192 kbps: 458 (2%)
The message Found xing header indicates the input file is a VBR
encoded files with a XING ancillary data header. The only two fields
updated by mpgedit are the frames (number of frames in encoding)
and bytes (total encoding size in bytes) fields. h_id indicates the
MPEG version; only 1=MPEG-1 is recognized. h_layer indicates
the MPEG layer; valid values are 1, 2 and 3. h_protect is 1 when
the copyright protection is enabled, and 0 when not enabled. samprate
is the audio sample rate for the encoding, in hertz (Hz). Both flags
and vbr_scale are values internal to the header.
When the -v option is used, only lines with the (1) tag in the
example above are displayed. These lines are displayed
for each one second of input file play time.
t= is the time offset into the input file.
fr= is the frame number for this time offset.
The file position in bytes (in both decimal and
hexadecimal formats) follows pos=.
When the -vv option is used, lines with the (2) tag are displayed
in addition to the (1) tag.
One (2) line is displayed for each frame present in the MPEG input file.
t= is the time offset into the input file,
and is displayed with 1 millisecond resolution.
br= is the frame encoding bitrate, in kb/s.
sz= is the frame size, in bytes.
fr= is the frame number for this time offset.
pos= is the file position in bytes,displayed in both decimal and
When the -vvv option is used, lines with the (3) tag are displayed
in addition to the (1) and (2) tags. These additional lines display all
information contained within an MPEG frame, and are displayed for each
frame present in the file. Each value is identified by name, followed by
the un-interpreted value, followed by the interpreted value, appearing
For all -v options listed above, a summary is printed after the
entire file is read. For CBR encoded files, the file name, frame count,
file size and play time are displayed. For VBR encoded files,
the frame minimum, maximum, and average encoding bitrate is displayed,
in addition to the CBR summary. Furthermore, for VBR encoded files,
a summary of the total number of frames encoded for each bitrate present
in the input file is displayed.
mpgedit requires configuration for the sound playback feature to work.
As root, run make install. For Linux as part of the installation,
the shared library loader is configured to search the directory
where mpgedit was installed. These are the actions performed by
the install process to configure the shared library loader:
echo /usr/local/lib >> /etc/ld.so.conf
Sound playback is implemented using two mechanisms: 1) an external command
line MP3 player capable of standard input file playback, and 2)
the MPGLIB decoder library that ships with the LAME project.
The default playback configuration uses the MPGLIB-based decoder
Two decoder plugin implementations ship with mpgedit: libdecoder_popen.so
and libdecoder_mpg123.so. libdecoder_popen.so will execute
the mp3decoder.sh script for file playback. libdecoder_mpg123.so is
implemented using the
MPGLIB decoder library present in LAME. This implementation also serves as
a sample implementation of a single process playback plugin that could be
ported to the Microsoft Windows(R) operating systems, and other
operating systems that do not support the popen() system call.
mpgedit attempts to load the playback plugin libmpgedit_decoder.so when
file playback is specified. When the decoder plugin is loaded, it is used for
file playback. When the decoder plugin cannot be loaded, the default
action is to execute the mp3decoder.sh script.
is installed as a symbolic link pointing to one of the playback plugins,
libdecoder_mpg123.so or libdecoder_popen.so. make install
installs the libdecoder_mpg123.so playback plugin.
libdecoder_popen.so can be installed manually when use of a command
line MP3 player is desired.
To use a different command line MP3 player, configure
libdecoder_popen.so as the playback plugin, then
edit the mp3decoder.sh file to call the desired MP3 player.
This shell script is then loaded by mpgedit when performing file playback,
and provides the flexibility to specify any MP3 player that can play
files from standard input.
IMPLEMENTATION LIMITATIONS AND ANOMALIES
Since release 0.6p1, mpgedit has been tested with MPEG 1 layer 1/2/3,
MPEG 2 layer 1/2/3 and MPEG 2.5 layer 3 files. Since MPEG 2.5 layer 1/2 files
have the same frame
header structure, it is assumed this program will function properly with
such files, although no testing on files encoded with this format has occurred.
While it is possible with mpgedit to join together files that consist of
differing encoding versions (MPEG-1 and MPEG-2, for example) and sample
rates (44.1KHz and 22.05KHz, for example), caution must be used.
Although such a file is technically a legal encoding, it is doubtful that
all (or any, for that matter) MP3 players will be able to correctly
render such a file.
Any ID3 tags present in input files are not present in the output from
an edit. Output files must be tagged to restore ID3 information.
mpgedit implements an MPEG audio frame header parser that is tolerant of
many encoder errors, corrupted data, and files with formats that are not
strictly MPEG audio
files. When such an encoding error is encountered, all data between the
last correctly encoded frame and the next recognized frame are silently skipped.
Other programs, such as mp3_check, perform a more detailed validity
report where errors occur, and are likely to be more robust when handling
corrupted data files.
Many playback problems present in releases of mpgedit prior to
version 0.6p1 have been fixed. Using the libdecoder_mpg123.so
plugin, mpgedit properly plays all of the ISO MPEG conformance
files, as well as MPEG 2/2.5 files encoded using lame.
Two exceptions to the above can be noted. Win32 does not properly
handle MPEG 2/2.5 files encoded at with a sample rate of 11025Hz/mono. A work
around in the libdecoder_mpg123.so decoder plugin is implemented,
but the sound quality suffers. The MPEG 1 layer 1 mono test file
http://mpgedit.org/mpgedit/testdata/mpeg1/layer1/fl4.mp1 does not
render properly. All the data used to exercise mpgedit is located
During development, the previous name of the program was mp3edit.
The final name mpgedit was settled on after much development
occurred. Because of this, many source files and function
names are called mp3_. You will also see mpeg_ instead of mpg_ in
ACKNOWLEDGEMENTS AND HISTORY
The first prototype implementation of MP3 file editing was based upon
the mp3_check program, written by Eric Bullen,
http://sourceforge.net/projects/mp3check. Because the project goals
are different than mpgedit, the idea of integrating editing functionality
into mp3_check was abandoned. Many of the current command line options
for mpgedit can be traced to the early prototype work done with mp3_check.
mpgedit is a completely independent implementation from the early mp3_check
editing prototype. While some of the early ideas from this prototype
still exist in mpgedit, everything has been re-implemented.
Finding reference material sufficiently complete to implement mpgedit was
difficult. The O'Reilly & Associates book "MP3: The Definitive Guide" by
Scot Hacker http://www.oreilly.com/catalog/mp3/,
while accurate in its description of the MPEG audio file frame header
structure, did not contain sufficient detail to fully implement the
MPEG file parsing functionality. The document that proved invaluable
for completing the MPEG audio frame header parsing code was written by
Predrag Supurovic, http://www.dv.co.yu/mpgscript/mpeghdr.htm.
The MPGLIB decoding engine comes from the MPG123 package, written
by Michael Hipp (www.mpg123.de). MPGLIB is released under the GPL.
The version of MPGLIB used for building the libdecoder_mpg123.so decoder
plugin comes from the 3.90 alpha 7 version of LAME
Earlier versions of LAME do not include a shared library build of MPGLIB,
which is needed when building the decoder plugin. The MPGLIB that comes with
mpg123-0.59r can also be used when linking the libdecoder_mpg123.so
plugin. However, LAME appears to have fixed some bugs that mpg123 has not.
xmpgedit(1), mp3decoder.sh(1), decoder.so(1),
- COMMAND LINE OPTIONS
- INTERACTIVE MODE COMMANDS
- CURSOR MOVEMENT
- EDITING COMMANDS
- AUTOMATIC EDITING
- PLAYBACK CONFIGURATION
- IMPLEMENTATION LIMITATIONS AND ANOMALIES
- ACKNOWLEDGEMENTS AND HISTORY
- SEE ALSO
This document was created by
using the manual pages.
Time: 17:55:39 GMT, December 04, 2004