1 decodebin: |
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2 |
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3 A bin with a sinkpad that decodes the data into raw formats. It works by sending |
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4 the input data through a typefind element and then recursively autoplugs elements |
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5 from the registry until a raw format is obtained. It will then create a new ghostpad |
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6 on itself to signal the app of the new pad. |
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7 |
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8 Decodebin will also remove pads when they are removed from the stream. |
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9 |
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10 TODO |
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11 - reuse of decoderbin, cleanup in READY state |
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12 - threading after demuxing? |
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13 - new_media events should be handled. |
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14 - caching of elements. |
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15 - abstract more elements, pads (typefind, ...); |
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16 |
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17 The autoplugging happens as follows: |
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18 |
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19 1) typefind is added internally to the bin. |
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20 2) the have_type signal is connected to typefind. |
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21 3) in the have_type callback the close_pad_link function is called |
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22 4) close_pad_link checks the type on the pad, if it is raw, a ghostpad |
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23 is created and autoplugging for that pad stops. |
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24 5) if the type of the pad is not raw, a list of possible elements that |
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25 can connect to this type is generated in find_compatibles. |
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26 6) try_to_link_1 with the element list is called. The function will loop |
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27 over the element list and will try to connect one of the elements to |
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28 the pad. If the link works, a call is made to close_link. |
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29 7) close_link loops over all the source pads of the element and |
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30 recursively calls 4) for any ALWAYS pad. For elements with |
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31 a SOMETIMES pad, a structure is set up and is passed to the callback |
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32 of the new_pad signal. |
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33 8) in the new_pad callback, 4) is called to try to autoplug the |
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34 new pad. |
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35 |
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36 |
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37 playbasebin: |
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38 |
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39 A bin with an uri property. It will find the right source element from the registry |
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40 and connect a decoderbin to it. When going to the PAUSED state, it will iterate the |
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41 decoderbin and listen for new pad signals from it. It will connect a queue to each |
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42 new pad and will iterate the decoderbin until one of the queues is filled. It is |
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43 assumed that by that time all the streams will be found so that when leaving the |
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44 PAUSED state, one can query the number of streams in the media file with the given |
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45 uri. |
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46 |
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47 Playbasebin internally groups related streams together in a GstPlayBaseGroup. This |
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48 is particulary important for chained oggs. Initially, a new group is created in |
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49 the 'building' state. All new streams will be added to the building group until |
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50 no-more-pads is signaled or one of the preroll queues overflows. When this happens, |
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51 the group is commited to a list of groups ready for playback. PlaybaseBin will then |
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52 attach a padprobe to each stream to figure out when it finished. It will remove |
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53 the current group and install the next playable group, then. |
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54 |
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55 Before going to the PLAYING state, it is possible to connect a custom element to |
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56 each of the streams. To do that, you have to add the element to the bin and then |
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57 connect the pad(s) from the stream(s). You do not have to add the elements in |
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58 a thread, the bin will take care of then when it's needed. You are allowed to use |
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59 threads inside the elements, of course. |
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60 The bin tries to be smart and doesn't add a queue when there is only one possible |
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61 stream. |
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62 |
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63 |
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64 TODO |
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65 - reuse, cleanup in ready state |
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66 - when the first pad is closed, it's possible that another dynamic element is |
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67 added somewhere so that we need a queue for the first pad as well. |
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68 |
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69 |
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70 playbin: |
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71 |
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72 Extends playbasebin, sets up default audiosink and videosink for first audio/video |
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73 stream detected. implements seeking and querying on the configured sinks. |
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74 |
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75 It also waits for new notifications from playbasebin about any new groups that are |
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76 becomming active. It then disconnects the sinks and reconnects them to the new |
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77 pads in the group. |
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78 |
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79 TODO |
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80 - reuse, refcounting, cleanup in READY state |
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81 - be smarter about replugging the sinks instead of removing them and readding them. |
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82 - Do not crap out when the audio device is in use. |
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83 |
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84 |
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85 general |
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86 |
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87 TODO |
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88 - playlist support. maybe use a playlist bin that streams the contents of the |
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89 playlist on a pad, interleaved with new_media events. Also add a tuner |
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90 interface while we're at it. |
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91 |
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