[FFmpeg-devel] [RFC] libavfilter audio - af_resample

[Michael Niedermayer]

On Wed, Jul 14, 2010 at 03:33:27AM -0700, S.N. Hemanth Meenakshisundaram wrote:
> Michael Niedermayer wrote:
>> On Tue, Jul 13, 2010 at 03:14:31AM -0700, S.N. Hemanth Meenakshisundaram 
>> wrote:
>>   
>>> Michael Niedermayer wrote:
>>>     
>>>> On Sat, Jul 10, 2010 at 11:37:54PM +0100, M?ns Rullg?rd wrote:
>>>>         
>>>>> Michael Niedermayer <michaelni at gmx.at> writes:
>>>>>
>>>>>             
>>> Of course, vf_scale internally calls libswscale while af_resample is 
>>> currently duplicating a lot of lavc's resample & audioconvert.c code 
>>> internally so I could make changes if necessary.
>>>
>>> Should I instead wrap audioconvert for sample format conversion (use 
>>> av_audio_convert) and wrap resample.c for channel mixing. Also, perhaps 
>>> af_resample should be renamed to reformat to avoid confusing with the 
>>> downsampling/upsampling in lavc resample2.c
>>>     
>>
>> code should be efficient, not doing unneeded operations or copying.
>> It would also be a plus if the individual parts could be used without
>> avfilter.
>>
>>
>> [...]
>>   
> Hi All,
>
> Attached is a patch for af_resample.c to avoid double free and so it works 
> with the common Pix Formats/Sample Formats enum. This only shows 
> differences from the previous version sent.
>
> If no conversions are required, it just passes on the buffer to the next 
> filter.
>
> I'll update libavfilter.texi with usage info. Since individual parts need 
> to be used externally, I will rewrite this to wrap available lavc code 
> wherever possible.
>
> Regards,
> Hemanth
>

>  af_resample.c |   31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
> 3f6958a9d58e84b84f6b399c94af27264f8c9774  resample_new.diff
> diff --git a/libavfilter/af_resample.c b/libavfilter/af_resample.c
> index a7ddd70..d0f157b 100644
> --- a/libavfilter/af_resample.c
> +++ b/libavfilter/af_resample.c
> @@ -38,6 +38,7 @@ typedef struct {
>      int64_t out_channel_layout;        ///< output channel layout
>  
>      int in_samples_nb;                 ///< stores number of samples in previous incoming buffer
> +    AVFilterSamplesRef *prev_samples;  ///< stores previous incoming buffer
>      AVFilterSamplesRef *s16_samples;   ///< stores temporary audio data in s16 sample format for channel layout conversions
>      AVFilterSamplesRef *temp_samples;  ///< stores temporary audio data in s16 sample format after channel layout conversions
>      AVFilterSamplesRef *out_samples;   ///< stores audio data after required sample format and channel layout conversions
> @@ -193,12 +194,17 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
>  static av_cold void uninit(AVFilterContext *ctx)
>  {
>      ResampleContext *resample = ctx->priv;
> -    if (resample->s16_samples)
> +    if (resample->s16_samples && resample->s16_samples != resample->prev_samples)
>          avfilter_unref_samples(resample->s16_samples);
> -    if (resample->temp_samples)
> +    if (resample->temp_samples && (resample->temp_samples != resample->prev_samples) &&
> +        (resample->temp_samples != resample->s16_samples))
>          avfilter_unref_samples(resample->temp_samples);
> -    if (resample->out_samples)
> +    if (resample->out_samples && (resample->out_samples != resample->prev_samples) &&
> +        (resample->out_samples != resample->s16_samples) &&
> +        (resample->out_samples != resample->temp_samples))
>          avfilter_unref_samples(resample->out_samples);
> +    if (resample->prev_samples)
> +        avfilter_unref_samples(resample->prev_samples);
>  }
>  
>  static int query_formats(AVFilterContext *ctx)

i think you should seperate variables that hold "primary" pointers
and ones that contain copies of them

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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