[FFmpeg-user] JPGs->video1 ; MOV -> Mp4 video2 ; Concatenate - video2 audio OK but video is slow . .

[Philip Rhoades]

Carl,

Thanks for responding! - see inline comments:


On 2019-03-27 07:22, Carl Eugen Hoyos wrote:
> 2019-03-26 21:15 GMT+01:00, Philip Rhoades <phil at pricom.com.au>:
> 
>> I converted 21 JPGs to a video with:
> 
> Usually, converting jpgs with the image2 input works better than 
> concat.


Right - I will try that.


>>    ffmpeg -f concat -i concat_demuxer1.txt -vf scale=1024:576 -r 29.97
> 
> This framerate is never correct, a possible frame rate is 30000/1001


Hmm . . I was just using what was reported for the frame for the MOVs . 
. so using:

   "-r 30000/1001"

is OK?


> You can add the audio already in this step.


I did have a few attempts at that but couldn't get it working so I 
resorted to a two-step process - I will have another look.


>> output1.mp4
>> 
>> I then added a silent audio track with:
>> 
>>    ffmpeg -ar 44100 -acodec pcm_s16le -f s16le -ac 2 -channel_layout 
>> 2.1
> 
> The channel number and layout do not match.


Should it be just "stereo"?


>> -i /dev/zero \
>>      -i output${i}.mp4 \
>>      -vcodec copy \
>>      -acodec aac \
>>      -shortest output${i}_silent.mp4
> 
>> I had another MOV file (fr=29.97) that I converted with:
>> 
>>    newfn=`basename $fn .MOV`
>>    ffmpeg  -i $fn -vf scale=1024:576 ./${newfn}.mp4
>> 
>> When I concatenate them with (and other converted JPGs and MOVS on the
>> end) using:
>> 
>>    ffmpeg -f concat -i inputs.txt -vcodec copy -acodec copy \
>> 2019-03-22_#1_XR_ClimateEmergencyDeclarationDayNSW_LoRes.mp4
>> 
>> the concat succeeds OK but when I play the video, the audio is OK but
>> then when it gets to the converted MOV section, people are moving in
>> slow motion . .
>> 
>> Another odd thing, the first 21 converted JPGs at 4 sec each correctly
>> shows 84 sec when viewed with mpv but when the converted MOV starts it
>> jumps to ~3m 50s . .
>> 
>> So there is at least one problem but maybe two?  Can anyone tell me 
>> what
>> I am missing?
> 
> You may have to re-encode, feel free to provide the complete, uncut
> console output.


OK, if you can respond to my questions above and if those changes don't 
improve the situation - I will supply the output.

Thanks!

Phil.
-- 
Philip Rhoades

PO Box 896
Cowra  NSW  2794
Australia
E-mail:  phil at pricom.com.au