Dear all, I would like to report an annoying behavior difference between S2API and the legacy DVB API (V3) when _reading_ the current tuning configuration. In short, API V3 is able to report the _actual_ tuning parameters as used by the driver and corresponding to the actual broadcast steam. On the other hand, S2API reports cached values which were specified in the tuning operation and these values may be generic (*_AUTO symbols) or even wrong. Logically, it seems that the difference is located in the API and not in the driver. Here is the configuration I test: Kernel 2.6.35.10-74.fc14.i686 (Fedora 14) Hauppauge WinTV-Nova-T-500 (dual DVB-T, DiBcom 3000MC/P) I tune to a frequency and let many parameters to their *_AUTO value: DTV_TRANSMISSION_MODE DTV_GUARD_INTERVAL DTV_CODE_RATE_HP DTV_CODE_RATE_LP The tuning is performed correctly and reception is effective. The tuner finds the right parameters. With API V3, after reading the frontend state (FE_GET_FRONTEND), the returned values are correct. I can see that actual code rate HP is 3/4, LP 1/2, transmission mode 8K and guard interval 1/8. However, on the same machine, after reading the frontend state using S2API (FE_GET_PROPERTY), all returned values are the *_AUTO values I specified while tuning. But there is worse. If I set a wrong parameter in the tuning operation, for instance guard interval 1/32, the API V3 returns the correct value which is actually used by the tuner (GUARD_INTERVAL_1_8), while S2API returns the "cached" value which was set while tuning (GUARD_INTERVAL_1_32). So, the driver is able 1) to find the correct actual parameter and 2) to report this actual value since API V3 returns it. But it seems that API V3 returns the actual tuning parameter as used by the driver while S2API returns a cached value which was used while tuning. This seems an annoying regression. An application is no longer able to determine the modulation parameter of an actual stream. As a final note, there is no difference if the tuning operation is performed using API V3 or S2API, the difference is only in the reading operation (FE_GET_FRONTEND vs. FE_GET_PROPERTY). Best regards, -Thierry -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
