[FFmpeg-devel] Add waveformat extensible support in wav muxer (SoC qualification task)

zhentan feng spyfeng
Sun Mar 29 05:51:57 CEST 2009


Hi

2009/3/28 Michael Niedermayer <michaelni at gmx.at>

> On Sat, Mar 28, 2009 at 06:47:25PM +0800, zhentan feng wrote:
> > Hi
> >
> > 2009/3/28 Benjamin Larsson <banan at ludd.ltu.se>
> >
> > > zhentan feng wrote:
> > >
> > >> Hi
> > >>
> > >> 2009/3/27 Benjamin Larsson <banan at ludd.ltu.se>
> > >>
> > >>
> > >>
> > >>> zhentan feng wrote:
> > >>>
> > >>>
> > >>>> Hi
> > >>>>
> > >>>> 2009/3/26 Benjamin Larsson <banan at ludd.ltu.se>
> > >>>>
> > >>>>
> > >>>>
> > >>>>> zhentan feng wrote:
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>>> Hi
> > >>>>>>
> > >>>>>> 2009/3/26 Michael Niedermayer <michaelni at gmx.at>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>> On Thu, Mar 26, 2009 at 01:19:00AM +0800, zhentan feng wrote:
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>> Hi,
> > >>>>>>>>
> > >>>>>>>> Here is patch for the small task of qualification tasks NO.30.
> > >>>>>>>> Based on the work of Benjamin Larsson, I generated the pathc as
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>> below.
> > >>>
> > >>>
> > >>>>      I think it must need further modifies.
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>> yes, iam not sure if this or benjamins patch was better
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>> I downloaded the 6-channel wav file from:
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>
> > >>>
> http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Samples/Microsoft/6_Channel_ID.wav
> > >>>
> > >>>
> > >>>>  ( and other typr wav files can acess here :
> > >>>>>>
> http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Samples.html
> > >>>>>> )
> > >>>>>>
> > >>>>>> 1) then I run ./ffmpeg_g -i 6_Channel_ID.wav channel4.wav
> > >>>>>>
> > >>>>>> I get the error:
> > >>>>>> Resampling with input channels greater than 2 unsupported.
> > >>>>>>
> > >>>>>> so I run another command:
> > >>>>>> 2) ./output_example test.wav
> > >>>>>> ./ffmpeg_g -i test.wav -ac 4 ch4.wav
> > >>>>>>
> > >>>>>> and enc->channels is 4, however enc->channel_layout is 0.
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>> Finally, I have 2 questions:
> > >>>>>>
> > >>>>>> 1) how to test the muxer works correctly?
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>> When the muxer works correctly it should be possible to transcode a
> wav
> > >>>>> file that contains the wavformatextensible header.
> > >>>>>
> > >>>>>  2) where to specify the enc->channel_layout?
> > >>>>>        It should be filled in by ffmpeg.c.
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>> I debug the commandline:
> > >>>> ./ffmpeg_g -i test.wav -ac 4 4ch.wav
> > >>>>
> > >>>> and found that the enc->channel_layout value is assigned from the
> input
> > >>>>
> > >>>>
> > >>> file
> > >>>
> > >>>
> > >>>> channel_layout. In this case, it is 0.
> > >>>> and it seems that "-channel_layout" option doesn't work.
> > >>>>
> > >>>> 1) is it need to refresh the channel_layout value according to the
> > >>>>
> > >>>>
> > >>> channels
> > >>>
> > >>>
> > >>>> in ffmpeg.c or in put_wav_header()?
> > >>>> 2) any tools to examine the output file is correct?
> > >>>>
> > >>>> zhentan feng
> > >>>>
> > >>>>
> > >>> Hi, this is the latest version of my patch. This adds the maybe
> correct
> > >>> GUID values. To really test this you need to find a wav file with a
> > >>> corrrect dwChannelMask. And then make sure that the muxer puts the
> same
> > >>> mask to the transcoded file. The output file should also be playable
> in
> > >>> windows.
> > >>>
> > >>> [...]
> > >>>
> > >>>
> > >>
> > >>
> > >> 1) I download the 6 channels sample wav file form the follow link:
> > >>
> > >>
> http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Samples/Microsoft/6_Channel_ID.wav
> > >>
> > >> then acoording to the new patch, I run the command:
> > >> ./ffmpeg -i 6_Channel_ID.wav output_ch6.wav
> > >>
> > >> the program run normaly, here is the output result.
> > >>
> > >> Input #0, wav, from '6_Channel_ID.wav':
> > >>  Duration: 00:00:05.83, bitrate: 4233 kb/s
> > >>    Stream #0.0: Audio: pcm_s16le, 44100 Hz, 6 channels
> > >> (FL|FR|FC|LFE|BL|BR), s16, 4233 kb/s
> > >> Output #0, wav, to 'output_ch6.wav':
> > >>    Stream #0.0: Audio: pcm_s16le, 44100 Hz, 6 channels
> > >> (FL|FR|FC|LFE|BL|BR), s16, 4233 kb/s
> > >> Stream mapping:
> > >>  Stream #0.0 -> #0.0
> > >> Press [q] to stop encoding
> > >> size=    3017kB time=5.84 bitrate=4233.7kbits/s
> > >> video:0kB audio:3017kB global headers:0kB muxing overhead 0.002201%
> > >>
> > >> 2) The file 6_Channel_ID.wav can be palyed by windows mediaplayer, but
> the
> > >> output_ch6.wav can't.
> > >>
> > >> I compared the two wav files and found that 6_Channel_ID.wav has 60
> more
> > >> bytes than output_ch6.wav
> > >> the 60 bytes are after WAVEFORMATEXTENSIBLE sturct,followed by the
> data.
> > >> Except for the 60 bytes, the two files are all the same.
> > >>
> > >> However, I noticed that the sample website says about 6_Channel_ID.wav
> > >> that
> > >> :"This file has a "cue " chunk with a count of zero cue points,
> followed
> > >> by
> > >> two empty cue point structures."
> > >>
> > >> my question is:
> > >> are the 60 bytes cue chunk? and how to handle this?
> > >>
> > >> zhentan feng
> > >> thanks
> > >>
> > >>
> > >
> > > Locate and look at the GUID in the original and the ffmpeg muxed file.
> They
> > > most likely differ.
> > >
> > > [..]
> > >
> >
> > yes. it's the GUID problem.
> > thanks.
> > here is the new patch.
> [...]
> > @@ -351,10 +357,21 @@
> >          put_le16(pb, 2); /* wav_extra_size */
> >          hdrsize += 2;
> >          put_le16(pb, enc->frame_size); /* wSamplesPerBlock */
> > -    } else if(enc->extradata_size){
> > -        put_le16(pb, enc->extradata_size);
> > +    } else if(enc->extradata_size || waveformatextensible){
> > +        if (waveformatextensible) {                     /* write
> WAVEFORMATEXTENSIBLE extensions */
> > +            put_le16(pb, enc->extradata_size+22);       /* 22 is the
> size of WAVEFORMATEXTENSIBLE-WAVEFORMATEX */
> > +            put_le16(pb, enc->bits_per_coded_sample);   /*
> ValidBitsPerSample || SamplesPerBlock || Reserved */
> > +            put_le32(pb, enc->channel_layout);          /* dwChannelMask
> */
> > +            put_le32(pb, enc->codec_tag);               /* GUID + next 3
> */
> > +            put_le32(pb, 0x00100000);
> > +            put_le32(pb, 0xAA000080);
> > +            put_le32(pb, 0x719B3800);
> > +            hdrsize += enc->extradata_size+22;
> > +        } else {
> > +            put_le16(pb, enc->extradata_size);
> > +            hdrsize += enc->extradata_size;
> > +        }
>
> what happens when waveformatextensible is 1 but one of the previous
> (else) if is true?
> does that fail or can that not happen at all?
>

here is new patch.
if(waveformatextensible)  is split from the if else chain.


>
> >          put_buffer(pb, enc->extradata, enc->extradata_size);
> > -        hdrsize += enc->extradata_size;
> >          if(hdrsize&1){
>
> id leave that and just add 22 in the if()


fixed.


-- 
Best wishes~
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