Rip and transcode using avconv - transcoding

I converted a video tape to DVD with an old converter,
then copied the DVD to my linux mint system to get a directory:
$ /bin/ls -s
12 VIDEO_TS.BUP
12 VIDEO_TS.IFO
56 VIDEO_TS.VOB
76 VTS_01_0.BUP
76 VTS_01_0.IFO
1048548 VTS_01_1.VOB
1048548 VTS_01_2.VOB
1048548 VTS_01_3.VOB
1020164 VTS_01_4.VOB
I run linux mint and want to use avconv to convert this to something
playable on my wife's macbook. But avconv gives error messages ...
$ avconv -v info -i VTS_01_1.VOB -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k tempa.mp4
avconv version 9.16-6:9.16-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers
built on Aug 10 2014 18:16:02 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
VTS_01_1.VOB: Invalid data found when processing input
I think the files are OK, since I can play this directory using
vlc .
Then vlc shows a menu screen with one possible option, "01", and when
I click that option I can view about 1 hour of video.
How can I convert the files in this directory to something
a macbook could play?
Thanks!

Turns out there's a better way. On the Linux side I used
handbrake to rip the DVD files to get .mkv files.
Then on the Mac OS X side, I found the installed quicktime
was lame, and wouldn't play .avi or .mkv files. So I
installed VLC, http://www.videolan.org/index.html,
and it plays the .mkv files well.

Related

avconv file protocol with rw_timeout and follow

I use avconv to convert a webm (still being recorded while converting) to h264.
I want avconv to wait while being written to the file.
https://libav.org/avconv.html#file says I can use the follow and rw_timeout option.
But when I use them with avconv 11.7 I always get the unregonized option response.
avconv -y -follow 1 -i file:/tmp/video/krtv/5405457303486272/recordings/video.webm -s hd720 -r 15 -strict experimental -c:v libx264 -c:a aac /tmp/video/krtv/5405457303486272/sized/video.mp4
avconv version 11.7, Copyright (c) 2000-2016 the Libav developers
built on Aug 29 2016 10:40:47 with gcc 4.7 (Debian 4.7.2-5)
Unrecognized option 'follow'.
Error splitting the argument list: Option not found
How to use these options on the file protocol with avconv 11.7?
Seems to be version 11.7 does not support this.
Compiling 12.alpha1 fixed this issue

How do you use youtube-dl to download live streams (that are live)?

Is it possible to use youtube-dl to download video from a .m3u8 stream file or other livestream formats?
When I copy the video URL into YouTube-dl it spits out:
[https # 0x7fc351416080] inflate return value: -3, incorrect header check
Last message repeated 15 times
After that it spits out of couple lines of red text that doesn't seem to want to copy in properly, so I took a snippet:
Does anyone know if this is possible?
I'll be using this Live Event from NASA TV as an example:
https://www.youtube.com/watch?v=21X5lGlDOfg
First, list the formats for the video:
youtube-dl --list-formats https://www.youtube.com/watch\?v\=21X5lGlDOfg
[youtube] 21X5lGlDOfg: Downloading webpage
[youtube] 21X5lGlDOfg: Downloading m3u8 information
[youtube] 21X5lGlDOfg: Downloading MPD manifest
[info] Available formats for 21X5lGlDOfg:
format code extension resolution note
91 mp4 256x144 HLS 197k , avc1.42c00b, 30.0fps, mp4a.40.5# 48k
92 mp4 426x240 HLS 338k , avc1.4d4015, 30.0fps, mp4a.40.5# 48k
93 mp4 640x360 HLS 829k , avc1.4d401e, 30.0fps, mp4a.40.2#128k
94 mp4 854x480 HLS 1380k , avc1.4d401f, 30.0fps, mp4a.40.2#128k
300 mp4 1280x720 3806k , avc1.4d4020, 60.0fps, mp4a.40.2 (best)
Pick the format you wish to download, and fetch the HLS m3u8 URL of the video from the manifest. I'll be using 94 mp4 854x480 HLS 1380k , avc1.4d401f, 30.0fps, mp4a.40.2#128k for this example:
youtube-dl -f 94 -g https://www.youtube.com/watch\?v\=21X5lGlDOfg
https://manifest.googlevideo.com/api/manifest/hls_playlist/expire/1592099895/ei/1y_lXuLOEsnXyQWYs4GABw/ip/81.190.155.248/id/21X5lGlDOfg.3/itag/94/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/goi/160/sgoap/gir%3Dyes%3Bitag%3D140/sgovp/gir%3Dyes%3Bitag%3D135/hls_chunk_host/r5---sn-h0auphxqp5-f5fs.googlevideo.com/playlist_duration/30/manifest_duration/30/vprv/1/playlist_type/DVR/initcwndbps/8270/mh/N8/mm/44/mn/sn-h0auphxqp5-f5fs/ms/lva/mv/m/mvi/4/pl/16/dover/11/keepalive/yes/beids/9466586/mt/1592078245/disable_polymer/true/sparams/expire,ei,ip,id,itag,source,requiressl,ratebypass,live,goi,sgoap,sgovp,playlist_duration,manifest_duration,vprv,playlist_type/sig/AOq0QJ8wRgIhAM2dGSece2shUTgS73Qa3KseLqnf85ca_9u7Laz7IDfSAiEAj8KHw_9xXVS_PV3ODLlwDD-xfN6rSOcLVNBpxKgkRLI%3D/lsparams/hls_chunk_host,initcwndbps,mh,mm,mn,ms,mv,mvi,pl/lsig/AG3C_xAwRQIhAJCO6kSwn7PivqMW7sZaiYFvrultXl6Qmu9wppjCvImzAiA7vkub9JaanJPGjmB4qhLVpHJOb9fZyhMEeh1EUCd-3Q%3D%3D/playlist/index.m3u8
Note that link could be different and it contains expiration timestamp, in this case 1592099895 (about 6 hours).
Now that you have the HLS playlist, you can open this URL in VLC and save it using "Record", or write a small ffmpeg command:
ffmpeg -i \
https://manifest.googlevideo.com/api/manifest/hls_playlist/expire/1592099895/ei/1y_lXuLOEsnXyQWYs4GABw/ip/81.190.155.248/id/21X5lGlDOfg.3/itag/94/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/goi/160/sgoap/gir%3Dyes%3Bitag%3D140/sgovp/gir%3Dyes%3Bitag%3D135/hls_chunk_host/r5---sn-h0auphxqp5-f5fs.googlevideo.com/playlist_duration/30/manifest_duration/30/vprv/1/playlist_type/DVR/initcwndbps/8270/mh/N8/mm/44/mn/sn-h0auphxqp5-f5fs/ms/lva/mv/m/mvi/4/pl/16/dover/11/keepalive/yes/beids/9466586/mt/1592078245/disable_polymer/true/sparams/expire,ei,ip,id,itag,source,requiressl,ratebypass,live,goi,sgoap,sgovp,playlist_duration,manifest_duration,vprv,playlist_type/sig/AOq0QJ8wRgIhAM2dGSece2shUTgS73Qa3KseLqnf85ca_9u7Laz7IDfSAiEAj8KHw_9xXVS_PV3ODLlwDD-xfN6rSOcLVNBpxKgkRLI%3D/lsparams/hls_chunk_host,initcwndbps,mh,mm,mn,ms,mv,mvi,pl/lsig/AG3C_xAwRQIhAJCO6kSwn7PivqMW7sZaiYFvrultXl6Qmu9wppjCvImzAiA7vkub9JaanJPGjmB4qhLVpHJOb9fZyhMEeh1EUCd-3Q%3D%3D/playlist/index.m3u8 \
-c copy output.ts
There is no need to pass anything to ffmpeg you can just grab the desired format, in this example, it was the "95" format.
So once you know that it is the 95, you just type:
youtube-dl -f 95 https://www.youtube.com/watch\?v\=6aXR-SL5L2o
that is to say:
youtube-dl -f <format number> <url>
It will begin generating on the working directory a <somename>.<probably mp4>.part which is the partially downloaded file, let it go and just press <Ctrl-C> to stop the capture.
The file will still be named <something>.part, rename it to <whatever>.mp4 and there it is...
The ffmpeg code:
ffmpeg -i $(youtube-dl -f <format number> -g <url>) -copy <file_name>.ts
also worked for me, but sound and video got out of sync, using just youtube-dl seemed to yield a better result although it too uses ffmpeg.
The downside of this approach is that you cannot watch the video while downloading, well you can open yet another FF or Chrome, but it seems that mplayer cannot process the video output till youtube-dl/ffmpeg are running.
Some websites with m3u streaming cannot be downloaded in a single youtube-dl step, you can try something like this :
$ URL=https://www.arte.tv/fr/videos/078132-001-A/cosmos-une-odyssee-a-travers-l-univers/
$ youtube-dl -F $URL | grep m3u
HLS_XQ_2 m3u8 1280x720 VA-STA, Allemand 2200k
HLS_XQ_1 m3u8 1280x720 VF-STF, Français 2200k
$ CHOSEN_FORMAT=HLS_XQ_1
$ youtube-dl -F "$(youtube-dl -gf $CHOSEN_FORMAT)"
[generic] master: Requesting header
[generic] master: Downloading webpage
[generic] master: Downloading m3u8 information
[info] Available formats for master:
format code extension resolution note
61 mp4 audio only 61k , mp4a.40.2
419 mp4 384x216 419k , avc1.66.30, mp4a.40.2
923 mp4 640x360 923k , avc1.77.30, mp4a.40.2
1737 mp4 720x406 1737k , avc1.77.30, mp4a.40.2
2521 mp4 1280x720 2521k , avc1.77.30, mp4a.40.2 (best)
$ youtube-dl --hls-prefer-native -f 1737 "$(youtube-dl -gf $CHOSEN_FORMAT $URL)" -o "$(youtube-dl -f $CHOSEN_FORMAT --get-filename $URL)"
[generic] master: Requesting header
[generic] master: Downloading webpage
[generic] master: Downloading m3u8 information
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 257
[download] Destination: Cosmos_une_odyssee_a_travers_l_univers__HLS_XQ_1__078132-001-A.mp4
[download] 0.9% of ~731.27MiB at 624.95KiB/s ETA 13:13
....
I have Written a small script to download the live youtube video, you may use as single command as well.
script it can be invoked simply as,
~/ytdl_lv.sh <URL> <output file name>
e.g.
~/ytdl_lv.sh https://www.youtube.com/watch?v=nX0sg1Gp-1 myfile.mp4
script is as simple as below,
#!/bin/bash
# ytdl_lv.sh
# Author Prashant
#
URL=$1
OUTNAME=$2
streamlink --hls-live-restart -o ${OUTNAME} ${URL} best
here the best is the stream quality, it also can be 144p (worst), 240p, 360p, 480p, 720p (best)
This answer has been completely rewritten on 19 Dec. 2022, after receiving the 6 downvotes.
How to download a live video? Follow the most-upvoted answer here, but use yt-dlp now wherever they use youtube-dl.
I recommend you use yt-dlp instead of youtube-dl. It's a fork off of youtube-dl and is much better-maintained and works much better. In the cases where youtube-dl gives me errors, yt-dlp works just fine. Also, in cases where youtube-dl downloads at 42 KiB/sec (which includes pretty much every time I use it--including 19 Dec. 2022 on Ubuntu 22.04), yt-dlp downloads at 86 MiB/sec, which is ~2100x faster, again, as tested on Ubuntu 22.04 seconds ago.
Tested on Ubuntu 22.04 on 19 Dec. 2022.
# Install yt-dlp
sudo apt update
sudo apt install yt-dlp
# Use it to download a video
# generally a smaller size; good quality
yt-dlp -f best https://www.youtube.com/watch?v=VUhQ6zEky0o
# bigger size; best quality
yt-dlp https://www.youtube.com/watch?v=VUhQ6zEky0o
See also my answer here where I explain this command a bit more: How to select video quality from youtube-dl?.
What youtube-dl errors did I see?
Tested on Ubuntu 18.04 and/or 20.04 on 28 Mar. 2021.
I tried following the the most-upvoted answer here but I'm getting the ERROR: VUhQ6zEky0o: YouTube said: Invalid parameters. error with youtube-dl and it's not working for me.
Sample live stream link: https://www.youtube.com/watch?v=VUhQ6zEky0o. My attempt, and the failure message:
$ youtube-dl --list-formats https://www.youtube.com/watch?v=VUhQ6zEky0o
[youtube] VUhQ6zEky0o: Downloading webpage
[youtube] VUhQ6zEky0o: Downloading video info webpage
ERROR: VUhQ6zEky0o: YouTube said: Invalid parameters.
Again, here's the error from above:
ERROR: VUhQ6zEky0o: YouTube said: Invalid parameters.
I tried youtube-dl with multiple live stream links while they were live. It didn't work for any of them. I got the error message above instead.
Solution
Use yt-dlp instead.
Last resort: use OBS studio to do a live screen capture
As a last resort, if you can't get youtube-dl nor yt-dlp to work, just do a live screen capture via OBS studio instead. Here are my detailed instructions on how to do that: Super User: How do you use OBS studio to perform screen capture (including to save live videos or make how-to tutorials)?.
This approach also works great, but is clearly not "downloading" the video stream in the same way.
As of 2023, youtube-dl seems to work fine, but note that sometimes the live stream separates the audio and video into distinct streams, then if you try to supply -f <preferred stream code> you will only get either the video or the audio.
The solution then is to simply not pass any argument, just youtube-dl https://address-to-the-stream.m3u8 and it will automatically download the best quality video stream and merge it transparently with the best audio stream via ffmpeg (tested on Windows 10).

Native iOS video player fails on HLS encrypted with openssl

I'm having an issue with encrypting HLS using openssl. As described here: Using openssl encryption for Apple's HTTP Live Streaming I'm using following script to encrypt TS files created by ffmpeg:
encyptionKeyFile="crypt.key"
openssl rand 16 > $encyptionKeyFile
encryptionKey=`cat $encyptionKeyFile | hexdump -e '16/1 "%02x"'`
splitFilePrefix="$fileName.split."
encryptedSplitFilePrefix="${splitFilePrefix}enc."
numberOfTsFiles=`ls ${splitFilePrefix}*.ts | wc -l`
for i in {0..$numberOfTsFiles}; do
initializationVector=`printf '%032x' $i`
openssl aes-128-cbc -e -in ${splitFilePrefix}$i.ts -out ${encryptedSplitFilePrefix}$i.ts -nosalt -iv $initializationVector -K $encryptionKey
rm ${splitFilePrefix}$i.ts
done
ffmpeg command used to generate TS file is following:
ffmpeg -i $file -codec copy -map 0 -f segment -vbsf h264_mp4toannexb -segment_list $mainPlaylistName -segment_time 10 ${splitFilePrefix}%d.ts
M3U8 playlist file looks like:
#EXTM3U
#EXT-X-VERSION:3
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-ALLOW-CACHE:YES
#EXT-X-KEY:METHOD=AES-128,URI=crypt.key
#EXT-X-TARGETDURATION:19
#EXTINF:11.875000,
BigBuckBunnyMovie.split.enc.0.ts
#EXTINF:11.166667,
BigBuckBunnyMovie.split.enc.1.ts
#EXTINF:12.500000,
BigBuckBunnyMovie.split.enc.2.ts
#EXTINF:12.166667,
BigBuckBunnyMovie.split.enc.3.ts
#EXTINF:8.375000,
...
#EXT-X-ENDLIST
I thought that it might be a problem with encoding or something with ffmpeg command format but the thing is that encrypted stream doesn't work on native iOS player (MPMoviePlayerController) but works fine on VLC. What is more, unencrypted stream (using TS files produced by ffmpeg) works on both native player and VLC!
Can you suggest me what can I do to be able to play it on native iOS video player?
Thanks for all your responses!
The draft spec states that the URI value is a quoted string. See section 3.4.4 of the draft spec.

How can I extract audio from video with ffmpeg? [closed]

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Improve this question
I tried the following command to extract audio from video:
ffmpeg -i Sample.avi -vn -ar 44100 -ac 2 -ab 192k -f mp3 Sample.mp3
but I get the following output
libavutil 50.15. 1 / 50.15. 1
libavcodec 52.72. 2 / 52.72. 2
libavformat 52.64. 2 / 52.64. 2
libavdevice 52. 2. 0 / 52. 2. 0
libavfilter 1.19. 0 / 1.19. 0
libswscale 0.11. 0 / 0.11. 0
libpostproc 51. 2. 0 / 51. 2. 0
SamplE.avi: Invalid data found when processing input
Can anyone help, please?
To extract the audio stream without re-encoding:
ffmpeg -i input-video.avi -vn -acodec copy output-audio.aac
-vn is no video.
-acodec copy says use the same audio stream that's already in there.
Read the output to see what codec it is, to set the right filename extension.
To encode a high quality MP3 or MP4 audio from a movie file (eg AVI, MP4, MOV, etc) or audio file (eg WAV), I find it's best to use -q:a 0 for variable bit rate and it's good practice to specify -map a to exclude video/subtitles and only grab audio:
ffmpeg -i sample.avi -q:a 0 -map a sample.mp3
If you want to extract a portion of audio from a video use the -ss option to specify the starting timestamp, and the -t option to specify the encoding duration, eg from 3 minutes and 5 seconds in for 45 seconds:
ffmpeg -i sample.avi -ss 00:03:05 -t 00:00:45.0 -q:a 0 -map a sample.mp3
The timestamps need to be in HH:MM:SS.xxx format or in seconds.
If you don't specify the -t option it will go to the end.
You can use the -to option instead of the -t option, if you want to specify the range, eg for 45 seconds: 00:03:05 + 45 = 00:03:50
Working example:
Download ffmpeg
Open a Command Prompt (Start > Run > CMD) or on a Mac/Linux open a Terminal
cd (the change directory command) to the directory with the ffmeg.exe, as depicted.
Issue your command and wait for the output file (or troubleshoot any errors)
Windows
Mac/Linux
Extract all audio tracks / streams
This puts all audio into one file:
ffmpeg -i input.mov -map 0:a -c copy output.mov
-map 0:a selects all audio streams only. Video and subtitles will be excluded.
-c copy enables stream copy mode. This copies the audio and does not re-encode it. Remove -c copy if you want the audio to be re-encoded.
Choose an output format that supports your audio format. See comparison of container formats.
Extract a specific audio track / stream
Example to extract audio stream #4:
ffmpeg -i input.mkv -map 0:a:3 -c copy output.m4a
-map 0:a:3 selects audio stream #4 only (ffmpeg starts counting from 0).
-c copy enables stream copy mode. This copies the audio and does not re-encode it. Remove -c copy if you want the audio to be re-encoded.
Choose an output format that supports your audio format. See comparison of container formats.
Extract and re-encode audio / change format
Similar to the examples above, but without -c copy. Various examples:
ffmpeg -i input.mp4 -map 0:a output.mp3
ffmpeg -i input.mkv -map 0:a output.m4a
ffmpeg -i input.avi -map 0:a -c:a aac output.mka
ffmpeg -i input.mp4 output.wav
Extract all audio streams individually
This input in this example has 4 audio streams. Each audio stream will be output as single, individual files.
ffmpeg -i input.mov -map 0:a:0 output0.wav -map 0:a:1 output1.wav -map 0:a:2 output2.wav -map 0:a:3 output3.wav
Optionally add -c copy before each output file name to enable stream copy mode.
Extract a certain channel
Use the channelsplit filter. Example to get the Front Right (FR) channel from a stereo input:
ffmpeg -i stereo.wav -filter_complex "[0:a]channelsplit=channel_layout=stereo:channels=FR[right]" -map "[right]" front_right.wav
channel_layout is the channel layout of the input. It is not automatically detected so you must provide the layout name.
channels lists the channel(s) you want to extract.
See ffmpeg -layouts for audio channel layout names (for channel_layout) and channel names (for channels).
Using stream copy mode (-c copy) is not possible to use when filtering, so the audio must be re-encoded.
See FFmpeg Wiki: Audio Channels for more examples.
What's the difference between -map and -vn?
ffmpeg has a default stream selection behavior that will select 1 stream per stream type (1 video, 1 audio, 1 subtitle, 1 data).
-vn is an old, legacy option. It excludes video from the default stream selection behavior. So audio, subtitles, and data are still automatically selected unless told not to with -an, -sn, or -dn.
-map is more complicated but more flexible and useful. -map disables the default stream selection behavior and ffmpeg will only include what you tell it to with -map option(s). -map can also be used to exclude certain streams or stream types. For example, -map 0 -map -0:v would include all streams except all video.
See FFmpeg Wiki: Map for more examples.
Errors
Invalid audio stream. Exactly one MP3 audio stream is required.
MP3 only supports 1 audio stream. The error means you are trying to put more than 1 audio stream into MP3. It can also mean you are trying to put non-MP3 audio into MP3.
WAVE files have exactly one stream
Similar to above.
Could not find tag for codec in stream #0, codec not currently supported in container
You are trying to put an audio format into an output that does not support it, such as PCM (WAV) into MP4.
Remove -c copy, choose a different output format (change the file name extension), or manually choose the encoder (such as -c:a aac).
See comparison of container formats.
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
This is a useless, generic error. The actual, informative error should immediately precede this generic error message.
Seems like you're extracting audio from a video file & downmixing to stereo channel.
To just extract audio (without re-encoding):
ffmpeg.exe -i in.mp4 -vn -c:a copy out.m4a
To extract audio & downmix to stereo (without re-encoding):
ffmpeg.exe -i in.mp4 -vn -c:a copy -ac 2 out.m4a
To generate an mp3 file, you'd re-encode audio:
ffmpeg.exe -i in.mp4 -vn -ac 2 out.mp3
-c (select codecs) & -map (select streams) options:
-c:a -> select best supported audio (transcoded)
-c:a copy -> best supported audio (copied)
-map 0:a -> all audio from 1st (audio) input file (transcoded)
-map 0:0 -> 1st stream from 1st input file (transcoded)
-map 1:a:0 -> 1st audio stream from 2nd (audio) input file (transcoded)
-map 1:a:1 -c:a copy -> 2nd audio stream from 2nd (audio)input file (copied)
ffmpeg -i sample.avi will give you the audio/video format info for your file. Make sure you have the proper libraries configured to parse the input streams. Also, make sure that the file isn't corrupt.
The command line is correct and works on a valid video file. I would make sure that you have installed the correct library to work with mp3, install lame o probe with another audio codec.
Usually
ffmpeg -formats
or
ffmpeg -codecs
would give sufficient information so that you know more.
To encode mp3 audio ffmpeg.org shows the following example:
ffmpeg -i input.wav -codec:a libmp3lame -qscale:a 2 output.mp3
I extracted the audio from a video just by replacing input.wav with the video filename. The 2 means 190 kb/sec. You can see the other quality levels at my link above.
For people looking for the simpler way to extract audio from a video file while retaining the original video file's parameters, you can use:
ffmpeg -i <video_file_name.extension> <audio_file_name.extension>
For example, running:
ffmpeg -i screencap.mov screencap.mp3
extracts an mp3 audio file from a mov video file.
Here's what I just used:
ffmpeg -i my.mkv -map 0:3 -vn -b:a 320k my.mp3
Options explanation:
my.mkv is a source video file, you can use other formats as well
-map 0:3 means I want 3rd stream from video file. Put your N there - video files often has multiple audio streams; you can omit it or use -map 0:a to take the default audio stream. Run ffprobe my.mkv to see what streams does the video file have.
my.mp3 is a target audio filename, and ffmpeg figures out I want an MP3 from its extension. In my case the source audio stream is ac3 DTS and just copying wasn't what I wanted
320k is a desired target bitrate
-vn means I don't want video in target file
Creating an audio book from several video clips
First, extracting the audio (as `.m4a) from a bunch of h264 files:
for f in *.mp4; do ffmpeg -i "$f" -vn -c:a copy "$(basename "$f" .mp4).m4a"; done
the -vn output option disables video output (automatic selection or mapping of any video stream). For full manual control see the -map option.
Optional
If there's an intro of, say, 40 seconds, you can skip it with the -ss parameter:
for f in *.m4a; do ffmpeg -i "$f" -ss 00:00:40 -c copy crop/"$f"; done
To combine all files in one:
ffmpeg -f concat -safe 0 -i <(for f in ./*.m4a; do echo "file '$PWD/$f'"; done) -c copy output.m4a
If the audio wrapped into the avi is not mp3-format to start with, you may need to specify -acodec mp3 as an additional parameter. Or whatever your mp3 codec is (on Linux systems its probably -acodec libmp3lame). You may also get the same effect, platform-agnostic, by instead specifying -f mp3 to "force" the format to mp3, although not all versions of ffmpeg still support that switch. Your Mileage May Vary.
To extract without conversion I use a context menu entry - as file manager custom action in Linux - to run the following (after having checked what audio type the video contains; example for video containing ogg audio):
bash -c 'ffmpeg -i "$0" -map 0:a -c:a copy "${0%%.*}".ogg' %f
which is based on the ffmpeg command ffmpeg -i INPUT -map 0:a -c:a copy OUTPUT.
I have used -map 0:1 in that without problems, but, as said in a comment by #LordNeckbeard, "Stream 0:1 is not guaranteed to always be audio. Using -map 0:a instead of -map 0:1 will avoid ambiguity."
Use -b:a instead of -ab as -ab is outdated now, also make sure your input file path is correct.
To extract audio from a video I have used below command and its working fine.
String[] complexCommand = {"-y", "-i", inputFileAbsolutePath, "-vn", "-ar", "44100", "-ac", "2", "-b:a", "256k", "-f", "mp3", outputFileAbsolutePath};
Here,
-y - Overwrite output files without asking.
-i - FFmpeg reads from an arbitrary number of input “files” specified by the -i option
-vn - Disable video recording
-ar - sets the sampling rate for audio streams if encoded
-ac - Set the number of audio channels.
-b:a - Set the audio bitrate
-f - format
Check out this for my complete sample FFmpeg android project on GitHub.

converting video files to .flv format in grails

I am developing a web-application in grails.In that I have implemented video's playing option.For playing video I used the flashplayer plugin .It is working.Now I am planning to implement the feature that user's also can upload their video's.After uploading the video files how to convert those video files to .flv format?
or
Does flash player plays all the video formats?I tried with .wmv file .It is not working.
Can anyone provide help on this?
Thanks
Flash can only play FLVs, and h.264 encoded videos (e.g. mp4, f4v). You can convert video into any of these formats using FFmpeg. If you're using Windows, you can get some pre-built binaries here.
Sample command-line that should convert inputfile.avi to an flv with an audio bitrate of 48kbps, and a video bitrate of 224kbps (might need to substitute libmp3lame for mp3 depending on version of ffmpeg):
ffmpeg -i inputfile.avi -s 640x480 -y -f flv -acodec mp3 -ac 1 -ab 48k -b 224k -ar 22050 outputfile.flv
Sample for h.264 / aac:
ffmpeg -i inputfile.avi -s 640x480 -y -f mp4 -vcodec libx264 -acodec libfaac -ab 48k -b 224k -ar 22050 outputfile.mp4

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