[FFmpeg-user] how re and im work in afftfilt

[Adam Puckett via ffmpeg-user]

Hi,

I'd like to know how the re and im variables in afftfilt work and what afftfilt 
is capable of. I'm new to frequency domain data and have some ideas in mind but 
not sure how to put them into practice. Can I for example implement filters or 
pitch correction/tracking? Or formant correction?

Thanks, Adam
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[FFmpeg-user] frequency modulation

[Adam Puckett]

I have another aevalsrc related question, so I thought I'd make a new
thread. How would I perform frequency modulation of a waveform? I'd
assume it would be with a formula similar to the exponential frequency
sweep I had a question about earlier?
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Re: [FFmpeg-user] aevalsrc question

[Adam Puckett]

On 12/20/16, Muhammad Faiz <mfc...@gmail.com> wrote:
> On 12/20/16, Adam Puckett <signalsender...@gmail.com> wrote:
>> On 12/19/16, Nicolas George <geo...@nsup.org> wrote:
>>> Oh, good catch. I should have remembered this task needed a primitive
>>> function, not just a multiplication.
>>>
>>> Regards,
>>>
>>> --
>>>   Nicolas George
>>>
>> What do I need to do to make the formula right?
>
> Just do the reverse.
> Given freq(t) = 262 * 2^(t/10)
> w(t) = 2*PI * 262 * 2^(t/10)
> ph(t) = integral of w(t) dt
>   = 2*PI * 262 * 10/log(2) * 2^(t/10) + arbitrary constant
>
> Thx.
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Thanks, that worked! But the question is: why? I don't quite
understand why I had to put in the log(2) expression.

On a related note, I've looked at a formula that does  linear
interpolation (one of the example scripts for Praat
(http://praat.org/)), and there is a division by 2 in the script; is
this for a similar reason? (For arbitrary targeted frequencies, I'm
assuming I would have to use a log(highestfreq/lowestfreq) in place of
the log(2)?)

Thanks
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Re: [FFmpeg-user] aevalsrc question

[Adam Puckett]

On 12/19/16, Nicolas George  wrote:
> Oh, good catch. I should have remembered this task needed a primitive
> function, not just a multiplication.
>
> Regards,
>
> --
>   Nicolas George
>
What do I need to do to make the formula right?
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Re: [FFmpeg-user] aevalsrc question

[Adam Puckett]

On 12/19/16, Nicolas George <geo...@nsup.org> wrote:
> L'octidi 28 frimaire, an CCXXV, Adam Puckett a écrit :
>> When you say it "works" for you (I have to double the ^ to escape on
>> Windows),
>
> My condoleances.
>
>>  does it produce this file?
>
> Yes, approximatively. Are you just hearing Vorbis artifacts?
No, because when I ffplay the same command, or generate uncompressed
files, I hear the same thing. I've checked the math and nothing
appears to be wrong according to the documentation, because when t =
10, 10/10 = 1, 262*2^1 = 520, so the formula should produce a 520 Hz
sine at the end, but the resulting frequency at the end is close to 1
kHz. This is puzzling.
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Re: [FFmpeg-user] aevalsrc question

[Adam Puckett]

On 12/18/16, Nicolas George <geo...@nsup.org> wrote:
> L'octidi 28 frimaire, an CCXXV, Adam Puckett a écrit :
>> Some time ago I posted a question about sweeping from one frequency to
>> another using aevalsrc and the t parameter of the expression. My
>> command line was something like:
>>
>> ffmpeg -f lavfi -i aevalsrc=sin(262*2^^(t/10)*2*PI*t):d=10 test.ogg
>>
>> and I'm still hearing higher frequencies than the desired output. I'm
>> also trying lots of other variations in the formula, and I'm trying to
>> do it without loading and storing commands.
>>
>> What am I doing wrong and how an I fix this?
>
> You have a suspicious double circumflex. If I fix it, the command works
> for me.
>
> Regards,
>
> --
>   Nicolas George
>
When you say it "works" for you (I have to double the ^ to escape on
Windows), does it produce this file?


test.ogg
Description: audio/ogg
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Re: [FFmpeg-user] aevalsrc question

[Adam Puckett]

On 12/18/16, Paul B Mahol <one...@gmail.com> wrote:
> On 12/18/16, Adam Puckett <signalsender...@gmail.com> wrote:
>> Hey list,
>>
>> Some time ago I posted a question about sweeping from one frequency to
>> another using aevalsrc and the t parameter of the expression. My
>> command line was something like:
>>
>> ffmpeg -f lavfi -i aevalsrc=sin(262*2^^(t/10)*2*PI*t):d=10 test.ogg
>>
>> and I'm still hearing higher frequencies than the desired output. I'm
>> also trying lots of other variations in the formula, and I'm trying to
>> do it without loading and storing commands.
>>
>> What am I doing wrong and how an I fix this?
>
> I don't get what you want. Can you explain it with math and logic?
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What I'm trying to do is exponential interpolation from 262 Hz to 524
Hz over the duration of 10 seconds.
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[FFmpeg-user] aevalsrc question

[Adam Puckett]

Hey list,

Some time ago I posted a question about sweeping from one frequency to
another using aevalsrc and the t parameter of the expression. My
command line was something like:

ffmpeg -f lavfi -i aevalsrc=sin(262*2^^(t/10)*2*PI*t):d=10 test.ogg

and I'm still hearing higher frequencies than the desired output. I'm
also trying lots of other variations in the formula, and I'm trying to
do it without loading and storing commands.

What am I doing wrong and how an I fix this?

Adam
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Re: [FFmpeg-user] FFMPEG 3.2.2 - "could not find codec parameters"

[Adam Puckett]

On 12/18/16, Caio Cesar Moreira  wrote:
> Hi,
>
> I'm trying to dump video frames from a TS file but for some reason ffmpeg
> is failing.
>
> Command used: ffmpeg -i playlist.m3u8 -vcodec -r 1 "output_%04d.png"
> -loglevel 99
>
> m3u8 content:
>
> #EXTM3U
>
> #EXT-X-VERSION:3
>
> #EXT-X-TARGETDURATION:5
>
> #EXT-X-MEDIA-SEQUENCE:160983
>
> #EXT-X-PROGRAM-DATE-TIME:2016-12-17 13:08:01+00:00
>
> #EXT-X-KEY:METHOD=AES-128,URI="key.bin"
>
> #EXTINF:5.,
>
> myfile.ts
>
> #EXT-X-ENDLIST
>
> myfile.ts and key.bin are in the same folder as the m3u8 file.
>
> ==
> OUTPUT:
> ==
>
> ffmpeg version 3.2.2 Copyright (c) 2000-2016 the FFmpeg developers
>
>   built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
>
>   configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl
> --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx
> --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora
> --enable-libvorbis --enable-libx264 --enable-avfilter
> --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters
> --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc
> --arch=x86_64 --enable-runtime-cpudetect
>
>   libavutil  55. 34.100 / 55. 34.100
>
>   libavcodec 57. 64.101 / 57. 64.101
>
>   libavformat57. 56.100 / 57. 56.100
>
>   libavdevice57.  1.100 / 57.  1.100
>
>   libavfilter 6. 65.100 /  6. 65.100
>
>   libswscale  4.  2.100 /  4.  2.100
>
>   libswresample   2.  3.100 /  2.  3.100
>
>   libpostproc54.  1.100 / 54.  1.100
>
> Splitting the commandline.
>
> Reading option '-i' ... matched as input url with argument 'playlist.m3u8'.
>
> Reading option '-vcodec' ... matched as option 'vcodec' (force video codec
> ('copy' to copy stream)) with argument '-r'.
>
> Reading option '1' ... matched as output url.
>
> Reading option 'output_%04d.png' ... matched as output url.
>
> Reading option '-loglevel' ... matched as option 'loglevel' (set logging
> level) with argument '99'.
>
> Finished splitting the commandline.
>
> Parsing a group of options: global .
>
> Applying option loglevel (set logging level) with argument 99.
>
> Successfully parsed a group of options.
>
> Parsing a group of options: input url playlist.m3u8.
>
> Successfully parsed a group of options.
>
> Opening an input file: playlist.m3u8.
>
> [file @ 0x7fd5f850daa0] Setting default whitelist 'file,crypto'
>
> Probing hls,applehttp score:100 size:245
>
> [hls,applehttp @ 0x7fd5f9002600] Format hls,applehttp probed with size=2048
> and score=100
>
> [hls,applehttp @ 0x7fd5f9002600] new_program: id=0x
>
> [hls,applehttp @ 0x7fd5f9002600] HLS request for url
> 'globo-sp1_2564-1481980676-18500029200.ts', offset 0, playlist 0
>
> [AVIOContext @ 0x7fd5f850e1a0] Statistics: 16 bytes read, 0 seeks
>
> Probing mp3 score:1 size:2048
>
> Probing mpeg score:25 size:2048
>
> Probing mpegts score:50 size:2048
>
> Format mpegts probed with size=2048 and score=50
>
> score: 44, dvhs_score: -1, fec_score: -3
>
> [mpegts @ 0x7fd5f900c200] Filter: pid=0x11 type=1
>
> [mpegts @ 0x7fd5f900c200] Filter: pid=0x0 type=1
>
> [AVIOContext @ 0x7fd5f850e1c0] Statistics: 1733924 bytes read, 0 seeks
>
> [mpegts @ 0x7fd5f900c200] tuning done
>
> [hls,applehttp @ 0x7fd5f9002600] Before avformat_find_stream_info() pos:
> 245 bytes read:245 seeks:0 nb_streams:0
>
> [hls,applehttp @ 0x7fd5f9002600] No longer receiving playlist 0
>
> [hls,applehttp @ 0x7fd5f9002600] format: start_time: -9223372036854.775
> duration: 5.000 bitrate=0 kb/s
>
> [hls,applehttp @ 0x7fd5f9002600] After avformat_find_stream_info() pos: 245
> bytes read:245 seeks:0 frames:0
>
> playlist.m3u8: could not find codec parameters
>
> [AVIOContext @ 0x7fd5f850db20] Statistics: 245 bytes read, 0 seeks
>
> ==
>
> On a Macbook Pro: Darwin 15.6.0 Darwin Kernel Version 15.6.0: Thu Sep  1
> 15:01:16 PDT 2016; root:xnu-3248.60.11~2/RELEASE_X86_64 x86_64
> I tried an older version of FFMPEG (3.1.5) and I get another error message
> for the same command line, which is: Output file #0 does not contain any
> stream.
>
> Any idea of what's going on?
> Thanks in advance!
> Caio
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Please remove "-vcodec" from your command line.
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