[vlc-devel] [PATCH] opensles_android: conditional compile for native sample rate check

["zhilizhao(赵志立)"]

Hi Thomas,

> On Feb 1, 2021, at 5:19 PM, Thomas Guillem <thomas at gllm.fr> wrote:
> 
> Hello Zhao,
> 
> You need to check the sdk dynamically and not at compile time (__ANDROID_API__ is fixed at compile time, a minimum value, then the build run on different API verions).
> 

Yes, the disadvantage of compile time check is that it still do the check on higher Android version.
Since most devices support arm64 and Android support arm64 since 5.0, the disadvantage affect
apps with only armv7 shared library. The native sample rate check has a little cost, and runtime 
device api level check has a little cost too. Here is another solution, do runtime check only if
compile time check failed:

#if CHECK_NATIVE_SAMPLE_RATE
if (android_get_device_api_level() < 21 && aout_get_native_sample_rate(aout) < (int)fmt->i_rate) {
    result = SL_RESULT_UNKNOWN_ERROR;
} else
# endif
    …

How about this?


> On Sat, Jan 30, 2021, at 16:15, Zhao Zhili wrote:
>> From: Zhao Zhili <zhilizhao at tencent.com>
>> 
>> The android bug has been fixed since Android 5.0.
>> ---
>> modules/audio_output/opensles_android.c | 19 ++++++++++++-------
>> 1 file changed, 12 insertions(+), 7 deletions(-)
>> 
>> diff --git a/modules/audio_output/opensles_android.c 
>> b/modules/audio_output/opensles_android.c
>> index 5459c40f04..72a0ada7ae 100644
>> --- a/modules/audio_output/opensles_android.c
>> +++ b/modules/audio_output/opensles_android.c
>> @@ -58,6 +58,8 @@ JNIEnv *android_getEnv(vlc_object_t *p_obj, const 
>> char *psz_thread_name);
>>         goto error; \
>>     }
>> 
>> +#define CHECK_NATIVE_SAMPLE_RATE (__ANDROID_API__ < 21)
>> +
>> typedef SLresult (*slCreateEngine_t)(
>>         SLObjectItf*, SLuint32, const SLEngineOption*, SLuint32,
>>         const SLInterfaceID*, const SLboolean*);
>> @@ -356,6 +358,7 @@ static void PlayedCallback 
>> (SLAndroidSimpleBufferQueueItf caller, void *pContext
>>     vlc_mutex_unlock(&sys->lock);
>> }
>> 
>> +#if CHECK_NATIVE_SAMPLE_RATE
>> static int aout_get_native_sample_rate(audio_output_t *aout)
>> {
>>     JNIEnv *p_env;
>> @@ -376,6 +379,7 @@ static int aout_get_native_sample_rate(audio_output_t *aout)
>>     msg_Dbg(aout, "%s: %d", __func__, sample_rate);
>>     return sample_rate;
>> }
>> +#endif
>> 
>> 
>> /*****************************************************************************
>>  *
>> @@ -417,19 +421,20 @@ static int Start(audio_output_t *aout, 
>> audio_sample_format_t *restrict fmt)
>>     const SLInterfaceID ids2[] = { 
>> sys->SL_IID_ANDROIDSIMPLEBUFFERQUEUE, sys->SL_IID_VOLUME };
>>     static const SLboolean req2[] = { SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE 
>> };
>> 
>> -    if (aout_get_native_sample_rate(aout) >= (int)fmt->i_rate) {
>> -        result = CreateAudioPlayer(sys->engineEngine, 
>> &sys->playerObject, &audioSrc,
>> -                                    &audioSnk, sizeof(ids2) / 
>> sizeof(*ids2),
>> -                                    ids2, req2);
>> -    } else {
>> +#if CHECK_NATIVE_SAMPLE_RATE
>> +    if (aout_get_native_sample_rate(aout) < (int)fmt->i_rate) {
>>         // Don't try to play back a sample rate higher than the native 
>> one,
>>         // since OpenSL ES will try to use the fast path, which 
>> AudioFlinger
>>         // will reject (fast path can't do resampling), and will end 
>> up with
>>         // too small buffers for the resampling. See 
>> http://b.android.com/59453
>> -        // for details. This bug is still present in 4.4. If it is 
>> fixed later
>> -        // this workaround could be made conditional.
>> +        // for details. This bug is fixed in 5.0
>>         result = SL_RESULT_UNKNOWN_ERROR;
>>     }
>> +    else
>> +#endif
>> +        result = CreateAudioPlayer(sys->engineEngine, 
>> &sys->playerObject, &audioSrc,
>> +                                    &audioSnk, sizeof(ids2) / 
>> sizeof(*ids2),
>> +                                    ids2, req2);
>>     if (unlikely(result != SL_RESULT_SUCCESS)) {
>>         /* Try again with a more sensible samplerate */
>>         fmt->i_rate = 44100;
>> -- 
>> 2.28.0
>> 
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