I have a problem that I am struggling to resolve. When I convert a video recorded using my Sony Camcorder from MPG to FLV, using FFMPEG, I lose the sound. I have done a little reading, and am currently struggling to fix this problem, but I think that is has something to do with some sound codecs not being installed. One one site I have read:

“By default flv selects mp3 audio but that is not configured in your
ffmpeg. Install lame, make distclean, add –enable-mp3lame to configure
command, make, retry. Some containers select default codecs that may not be
installed, and do so silently” – from mplayerhq.hu

So, looks like I need to install something, but what and how? Maybe there is something listed in the synaptic package manager that I can install……

I have recently bought a Sony DCR-SR35E Hard Disc Drive Handycam to film my baby son, but was struggling to find a way to showing the videos online, without having to resort to using public video sharing portals such as YouTube.

The solution is to use FFMPEG to convert the .mpg files (which Sony Camcorders record in) and then set up a simple flash video viewer. I am fortunate in that a good friend knocked up some code for me to show the videos, and pointed me in the right direction to get them playing.

To convert the .mpg file into a .flv one, I installed FFMPEG onto my Linux machine, and copied all the videos files over to there. Installing FFMPEG was easy using the Synaptic Package Manager which comes as standard on Ubuntu. Once installed, I simple navigated to the directory in which the MPG files were stored and then entered the following command:

ffmpeg -i camcordervideo.MPG -f flv newfile.flv

This worked OK, but not ideal. The thing about FFMPEG is that there are a plethora of options, and this created a new file based on default settings. The file created was too compressed for my liking, and had no sound. It is OK for now, but I now need to review the manual (man ffmpeg) to learn the various transcoding options to get better quality image and to keep the sound.

If you know the best commands for converting mpg to vlf, please let me know, so that I can compile a list of the most useful commands.

Here is the out put of the ffmpeg manual:

NAME
ffmpeg – FFmpeg video converter

SYNOPSIS
ffmpeg [[infile options][-i infile]]… {[outfile options] outfile}…

DESCRIPTION
If no input file is given, audio/video grabbing is done.

As a general rule, options are applied to the next specified file. For example, if you give the -b 64 option, it
sets the video bitrate of the next file. The format option may be needed for raw input files.

By default, FFmpeg tries to convert as losslessly as possible: It uses the same audio and video parameters for the
outputs as the one specified for the inputs.

OPTIONS
Main options

-L Show license.

-h Show help.

-formats
Show available formats, codecs, protocols, …

-f fmt
Force format.

-i filename
input filename

-y Overwrite output files.

-t duration
Set the recording time in seconds. “hh:mm:ss[.xxx]” syntax is also supported.

-ss position
Seek to given time position in seconds. “hh:mm:ss[.xxx]” syntax is also supported.

-title string
Set the title.

-author string
Set the author.

-copyright string
Set the copyright.

-comment string
Set the comment.

-target type
Specify target file type (“vcd”, “svcd”, “dvd”, “dv”, “pal-vcd”, “ntsc-svcd”, … ). All the format options
(bitrate, codecs, buffer sizes) are then set automatically. You can just type:

ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg

Nevertheless you can specify additional options as long as you know they do not conflict with the standard, as
in:

ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg

-hq Activate high quality settings.

-itsoffset offset
Set the input time offset in seconds. “[-]hh:mm:ss[.xxx]” syntax is also supported. This option affects all
the input files that follow it. The offset is added to the timestamps of the input files. Specifying a posi‐
tive offset means that the corresponding streams are delayed by ’offset’ seconds.

Video Options

-b bitrate
Set the video bitrate in kbit/s (default = 200 kb/s).
-r fps
Set frame rate (default = 25).

-s size
Set frame size. The format is wxh (default = 160×128). The following abbreviations are recognized:

sqcif
128×96

qcif
176×144

cif 352×288

4cif
704×576

-aspect aspect
Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).

-croptop size
Set top crop band size (in pixels).

-cropbottom size
Set bottom crop band size (in pixels).

-cropleft size
Set left crop band size (in pixels).

-cropright size
Set right crop band size (in pixels).

-padtop size
Set top pad band size (in pixels).

-padbottom size
Set bottom pad band size (in pixels).
-padleft size
Set left pad band size (in pixels).

-padright size
Set right pad band size (in pixels).

-padcolor (hex color)
Set color of padded bands. The value for padcolor is expressed as a six digit hexadecimal number where the
first two digits represent red, the middle two digits green and last two digits blue (default = 000000
(black)).

-vn Disable video recording.

-bt tolerance
Set video bitrate tolerance (in kbit/s).

-maxrate bitrate
Set max video bitrate tolerance (in kbit/s).

-minrate bitrate
Set min video bitrate tolerance (in kbit/s).

-bufsize size
Set rate control buffer size (in kbit).

-vcodec codec
Force video codec to codec. Use the “copy” special value to tell that the raw codec data must be copied as is.

-sameq
Use same video quality as source (implies VBR).

-pass n
Select the pass number (1 or 2). It is useful to do two pass encoding. The statistics of the video are
recorded in the first pass and the video is generated at the exact requested bitrate in the second pass.

-passlogfile file
Set two pass logfile name to file.
Advanced Video Options

-g gop_size
Set the group of pictures size.

-intra
Use only intra frames.

-qscale q
Use fixed video quantiser scale (VBR).

-qmin q
minimum video quantiser scale (VBR)

-qmax q
maximum video quantiser scale (VBR)

-qdiff q
maximum difference between the quantiser scales (VBR)

-qblur blur
video quantiser scale blur (VBR)

-qcomp compression
video quantiser scale compression (VBR)

-rc_init_cplx complexity
initial complexity for single pass encoding

-b_qfactor factor
qp factor between P- and B-frames

-i_qfactor factor
qp factor between P- and I-frames

-b_qoffset offset
qp offset between P- and B-frames
-i_qoffset offset
qp offset between P- and I-frames

-rc_eq equation
Set rate control equation (default = “tex^qComp”).

-rc_override override
rate control override for specific intervals

-me method
Set motion estimation method to method. Available methods are (from lowest to best quality):

zero
Try just the (0, 0) vector.

phods
log
x1
epzs
(default method)

full
exhaustive search (slow and marginally better than epzs)

-dct_algo algo
Set DCT algorithm to algo. Available values are:

0 FF_DCT_AUTO (default)

1 FF_DCT_FASTINT

2 FF_DCT_INT

3 FF_DCT_MMX

4 FF_DCT_MLIB

5 FF_DCT_ALTIVEC

-idct_algo algo
Set IDCT algorithm to algo. Available values are:

0 FF_IDCT_AUTO (default)

1 FF_IDCT_INT

2 FF_IDCT_SIMPLE

3 FF_IDCT_SIMPLEMMX

4 FF_IDCT_LIBMPEG2MMX

5 FF_IDCT_PS2

6 FF_IDCT_MLIB

7 FF_IDCT_ARM

8 FF_IDCT_ALTIVEC

9 FF_IDCT_SH4

10 FF_IDCT_SIMPLEARM

-er n
Set error resilience to n.

1 FF_ER_CAREFUL (default)

2 FF_ER_COMPLIANT

3 FF_ER_AGGRESSIVE

4 FF_ER_VERY_AGGRESSIVE

-ec bit_mask
Set error concealment to bit_mask. bit_mask is a bit mask of the following values:

1 FF_EC_GUESS_MVS (default = enabled)

2 FF_EC_DEBLOCK (default = enabled)

-bf frames
Use ’frames’ B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).

-mbd mode
macroblock decision

0 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).

1 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.

2 FF_MB_DECISION_RD: rate distortion

-4mv
Use four motion vector by macroblock (MPEG-4 only).

-part
Use data partitioning (MPEG-4 only).

-bug param
Work around encoder bugs that are not auto-detected.

-strict strictness
How strictly to follow the standards.

-aic
Enable Advanced intra coding (h263+).

-umv
Enable Unlimited Motion Vector (h263+)

-deinterlace
Deinterlace pictures.

-interlace
Force interlacing support in encoder (MPEG-2 and MPEG-4 only). Use this option if your input file is inter‐
laced and you want to keep the interlaced format for minimum losses. The alternative is to deinterlace the
input stream with -deinterlace, but deinterlacing introduces losses.

-psnr
Calculate PSNR of compressed frames.

-vstats
Dump video coding statistics to vstats_HHMMSS.log.

-vhook module
Insert video processing module. module contains the module name and its parameters separated by spaces.

Audio Options

-ar freq
Set the audio sampling frequency (default = 44100 Hz).

-ab bitrate
Set the audio bitrate in kbit/s (default = 64).

-ac channels
Set the number of audio channels (default = 1).

-an Disable audio recording.

-acodec codec
Force audio codec to codec. Use the “copy” special value to specify that the raw codec data must be copied as
is.

Audio/Video grab options

-vd device
sEt video grab device (e.g. /dev/video0).

-vc channel
Set video grab channel (DV1394 only).

-tvstd standard
Set television standard (NTSC, PAL (SECAM)).

-dv1394
Set DV1394 grab.

-ad device
Set audio device (e.g. /dev/dsp).

Advanced options

-map file:stream
Set input stream mapping.

-debug
Print specific debug info.

-benchmark
Add timings for benchmarking.

-hex
Dump each input packet.

-bitexact
Only use bit exact algorithms (for codec testing).

-ps size
Set packet size in bits.

-re Read input at native frame rate. Mainly used to simulate a grab device.

-loop
Loop over the input stream. Currently it works only for image streams. This option is used for automatic
FFserver testing.

-loop_output number_of_times
Repeatedly loop output for formats that support looping such as animated GIF (0 will loop the output
infinitely).

-vsync parameter
Video sync method. Video will be stretched/squeezed to match the timestamps, it is done by duplicating and
dropping frames. With -map you can select from which stream the timestamps should be taken. You can leave
either video or audio unchanged and sync the remaining stream(s) to the unchanged one.

-async samples_per_second
Audio sync method. “Stretches/squeezes” the audio stream to match the timestamps, the parameter is the maximum
samples per second by which the audio is changed. -async 1 is a special case where only the start of the
audio stream is corrected without any later correction.

FFmpeg formula evaluator

When evaluating a rate control string, FFmpeg uses an internal formula evaluator.

The following binary operators are available: “+”, “-”, “*”, “/”, “^”.

The following unary operators are available: “+”, “-”, “(…)”.

The following functions are available:

sinh(x)
cosh(x)
tanh(x)
sin(x)
cos(x)
tan(x)
exp(x)
log(x)
squish(x)
gauss(x)
abs(x)
max(x, y)
min(x, y)
gt(x, y)
lt(x, y)
eq(x, y)
bits2qp(bits)
qp2bits(qp)

The following constants are available:

PI
E
iTex
pTex
tex
mv
fCode
iCount
mcVar
var
isI
isP
isB
avgQP
qComp
avgIITex
avgPITex
avgPPTex
avgBPTex
avgTex

EXAMPLES
Video and Audio grabbing

FFmpeg can use a video4linux compatible video source and any Open Sound System audio source:

ffmpeg /tmp/out.mpg

Note that you must activate the right video source and channel before launching FFmpeg with any TV viewer such as
xawtv () by Gerd Knorr. You also have to set the audio recording levels correctly with
a standard mixer.
Video and Audio file format conversion

* FFmpeg can use any supported file format and protocol as input:

Examples:

* You can use YUV files as input:

ffmpeg -i /tmp/test%d.Y /tmp/out.mpg

It will use the files:

/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc…

The Y files use twice the resolution of the U and V files. They are raw files, without header. They can be gener‐
ated by all decent video decoders. You must specify the size of the image with the -s option if FFmpeg cannot
guess it.

* You can input from a raw YUV420P file:

ffmpeg -i /tmp/test.yuv /tmp/out.avi

test.yuv is a file containing raw YUV planar data. Each frame is composed of the Y plane followed by the U and V
planes at half vertical and horizontal resolution.

* You can output to a raw YUV420P file:

ffmpeg -i mydivx.avi hugefile.yuv

* You can set several input files and output files:

ffmpeg -i /tmp/a.wav -s 640×480 -i /tmp/a.yuv /tmp/a.mpg

Converts the audio file a.wav and the raw YUV video file a.yuv to MPEG file a.mpg.

* You can also do audio and video conversions at the same time:
* You can set several input files and output files:

ffmpeg -i /tmp/a.wav -s 640×480 -i /tmp/a.yuv /tmp/a.mpg

Converts the audio file a.wav and the raw YUV video file a.yuv to MPEG file a.mpg.

* You can also do audio and video conversions at the same time:

ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2

Converts a.wav to MPEG audio at 22050Hz sample rate.

* You can encode to several formats at the same time and define a mapping from input stream to output streams:

ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0

Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. ’-map file:index’ specifies which input stream is
used for each output stream, in the order of the definition of output streams.

* You can transcode decrypted VOBs

ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi

This is a typical DVD ripping example; the input is a VOB file, the output an AVI file with MPEG-4 video and MP3
audio. Note that in this command we use B-frames so the MPEG-4 stream is DivX5 compatible, and GOP size is 300
which means one intra frame every 10 seconds for 29.97fps input video. Furthermore, the audio stream is
MP3-encoded so you need to enable LAME support by passing “–enable-mp3lame” to configure. The mapping is partic‐
ularly useful for DVD transcoding to get the desired audio language.

NOTE: To see the supported input formats, use “ffmpeg -formats”.

SEE ALSO
ffserver(1), ffplay(1) and the HTML documentation of ffmpeg.

AUTHOR Fabrice Bellard 2007-01-28