[FFmpeg-devel] doc/examples/decode_audio: read the audio data from data[0]

Submitted by Steven Liu on Oct. 8, 2019, 8:26 a.m.

Details

Message ID 20191008082627.4044-1-lq@chinaffmpeg.org
State New
Headers show

Commit Message

Steven Liu Oct. 8, 2019, 8:26 a.m.
only frame linesize[0] can get length size,
i have tested before patch like this:
ffmpeg -i /Users/liuqi/input.mp3 -codec:a ac3 -ac 5 a.ac3
./doc/examples/decode_audio a.ac3 a.pcm
ffplay -f f32le -ac 5 -ar 44100 a.pcm
there have problem.

no problem after this patch.

Reported-by: Bepartofyou
Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
---
 doc/examples/decode_audio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Paul B Mahol Oct. 8, 2019, 8:48 a.m.
On 10/8/19, Steven Liu <lq@chinaffmpeg.org> wrote:
> only frame linesize[0] can get length size,
> i have tested before patch like this:
> ffmpeg -i /Users/liuqi/input.mp3 -codec:a ac3 -ac 5 a.ac3
> ./doc/examples/decode_audio a.ac3 a.pcm
> ffplay -f f32le -ac 5 -ar 44100 a.pcm
> there have problem.
>
> no problem after this patch.
>
> Reported-by: Bepartofyou
> Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
> ---
>  doc/examples/decode_audio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/doc/examples/decode_audio.c b/doc/examples/decode_audio.c
> index 6c2a8ed550..4a81302ad3 100644
> --- a/doc/examples/decode_audio.c
> +++ b/doc/examples/decode_audio.c
> @@ -98,7 +98,7 @@ static void decode(AVCodecContext *dec_ctx, AVPacket *pkt,
> AVFrame *frame,
>          }
>          for (i = 0; i < frame->nb_samples; i++)
>              for (ch = 0; ch < dec_ctx->channels; ch++)
> -                fwrite(frame->data[ch] + data_size*i, 1, data_size,
> outfile);
> +                fwrite(frame->data[0] + data_size*i, 1, data_size,
> outfile);
>      }
>  }

OK, but check for case of planar sample format is missing.


>
> --
> 2.15.1
>
>
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
Hendrik Leppkes Oct. 8, 2019, 8:49 a.m.
On Tue, Oct 8, 2019 at 10:44 AM Steven Liu <lq@chinaffmpeg.org> wrote:
>
> only frame linesize[0] can get length size,
> i have tested before patch like this:
> ffmpeg -i /Users/liuqi/input.mp3 -codec:a ac3 -ac 5 a.ac3
> ./doc/examples/decode_audio a.ac3 a.pcm
> ffplay -f f32le -ac 5 -ar 44100 a.pcm
> there have problem.
>
> no problem after this patch.
>
> Reported-by: Bepartofyou
> Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
> ---
>  doc/examples/decode_audio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/doc/examples/decode_audio.c b/doc/examples/decode_audio.c
> index 6c2a8ed550..4a81302ad3 100644
> --- a/doc/examples/decode_audio.c
> +++ b/doc/examples/decode_audio.c
> @@ -98,7 +98,7 @@ static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame,
>          }
>          for (i = 0; i < frame->nb_samples; i++)
>              for (ch = 0; ch < dec_ctx->channels; ch++)
> -                fwrite(frame->data[ch] + data_size*i, 1, data_size, outfile);
> +                fwrite(frame->data[0] + data_size*i, 1, data_size, outfile);
>      }
>  }
>

This change is definitely not correct. Without further changes, all
this does is copy the same block up to "channels" times. But whats
with all the other channel?

The current code is correct for handling planar audio. (ie. S16P/FLTP,
for example), but not packed audio (ie. S16/FLT). If you want to
support both planar and packed, you will need more changes then this.

- Hendrik
Steven Liu Oct. 8, 2019, 8:52 a.m.
> 在 2019年10月8日,16:48,Paul B Mahol <onemda@gmail.com> 写道:
> 
> On 10/8/19, Steven Liu <lq@chinaffmpeg.org> wrote:
>> only frame linesize[0] can get length size,
>> i have tested before patch like this:
>> ffmpeg -i /Users/liuqi/input.mp3 -codec:a ac3 -ac 5 a.ac3
>> ./doc/examples/decode_audio a.ac3 a.pcm
>> ffplay -f f32le -ac 5 -ar 44100 a.pcm
>> there have problem.
>> 
>> no problem after this patch.
>> 
>> Reported-by: Bepartofyou
>> Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
>> ---
>> doc/examples/decode_audio.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/doc/examples/decode_audio.c b/doc/examples/decode_audio.c
>> index 6c2a8ed550..4a81302ad3 100644
>> --- a/doc/examples/decode_audio.c
>> +++ b/doc/examples/decode_audio.c
>> @@ -98,7 +98,7 @@ static void decode(AVCodecContext *dec_ctx, AVPacket *pkt,
>> AVFrame *frame,
>>         }
>>         for (i = 0; i < frame->nb_samples; i++)
>>             for (ch = 0; ch < dec_ctx->channels; ch++)
>> -                fwrite(frame->data[ch] + data_size*i, 1, data_size,
>> outfile);
>> +                fwrite(frame->data[0] + data_size*i, 1, data_size,
>> outfile);
>>     }
>> }
> 
> OK, but check for case of planar sample format is missing.
Hi Paul,

	I have no planar sample test file, i have read the comments of the linesize,
	i have known there maybe have planar audio, but i don’t know how to construct the sample :(
> 
> 
>> 
>> --
>> 2.15.1
>> 
>> 
>> 
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel@ffmpeg.org
>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> 
>> To unsubscribe, visit link above, or email
>> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
> 

Thanks
Steven
Paul B Mahol Oct. 9, 2019, 7:23 a.m.
On 10/8/19, Steven Liu <lq@chinaffmpeg.org> wrote:
>
>
>> 在 2019年10月8日,16:48,Paul B Mahol <onemda@gmail.com> 写道:
>>
>> On 10/8/19, Steven Liu <lq@chinaffmpeg.org> wrote:
>>> only frame linesize[0] can get length size,
>>> i have tested before patch like this:
>>> ffmpeg -i /Users/liuqi/input.mp3 -codec:a ac3 -ac 5 a.ac3
>>> ./doc/examples/decode_audio a.ac3 a.pcm
>>> ffplay -f f32le -ac 5 -ar 44100 a.pcm
>>> there have problem.
>>>
>>> no problem after this patch.
>>>
>>> Reported-by: Bepartofyou
>>> Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
>>> ---
>>> doc/examples/decode_audio.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/doc/examples/decode_audio.c b/doc/examples/decode_audio.c
>>> index 6c2a8ed550..4a81302ad3 100644
>>> --- a/doc/examples/decode_audio.c
>>> +++ b/doc/examples/decode_audio.c
>>> @@ -98,7 +98,7 @@ static void decode(AVCodecContext *dec_ctx, AVPacket
>>> *pkt,
>>> AVFrame *frame,
>>>         }
>>>         for (i = 0; i < frame->nb_samples; i++)
>>>             for (ch = 0; ch < dec_ctx->channels; ch++)
>>> -                fwrite(frame->data[ch] + data_size*i, 1, data_size,
>>> outfile);
>>> +                fwrite(frame->data[0] + data_size*i, 1, data_size,
>>> outfile);
>>>     }
>>> }
>>
>> OK, but check for case of planar sample format is missing.
> Hi Paul,
>
> 	I have no planar sample test file, i have read the comments of the
> linesize,
> 	i have known there maybe have planar audio, but i don’t know how to
> construct the sample :(

As nev poinited out, change is incorrect, you need to add support for
both planar and packed or drop patch completely.

>>
>>
>>>
>>> --
>>> 2.15.1
>>>
>>>
>>>
>>> _______________________________________________
>>> ffmpeg-devel mailing list
>>> ffmpeg-devel@ffmpeg.org
>>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>>
>>> To unsubscribe, visit link above, or email
>>> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>>
>
> Thanks
> Steven
>
>
>
>
>
>

Patch hide | download patch | download mbox

diff --git a/doc/examples/decode_audio.c b/doc/examples/decode_audio.c
index 6c2a8ed550..4a81302ad3 100644
--- a/doc/examples/decode_audio.c
+++ b/doc/examples/decode_audio.c
@@ -98,7 +98,7 @@  static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame,
         }
         for (i = 0; i < frame->nb_samples; i++)
             for (ch = 0; ch < dec_ctx->channels; ch++)
-                fwrite(frame->data[ch] + data_size*i, 1, data_size, outfile);
+                fwrite(frame->data[0] + data_size*i, 1, data_size, outfile);
     }
 }