在上播放mp4视频使用GStreamer

Question

我试图使用GStreamer在上播放一个视频文件。

我正在使用这里的"drop.avi“文件：https://www.engr.colostate.edu/me/facil/dynamics/avis.htm

我可以使用以下命令成功地播放该文件：

gst-launch-1.0 playbin uri=file:///home/mendel/coral/google-coral/example-object-tracker/gstreamer/drop.avi

现在我想尝试播放一个mp4文件。

我使用here中的以下命令转换了avi文件

ffmpeg -i drop.avi -an -vf "scale=960:540,format=yuv420p" -colorspace bt470bg -color_range tv -color_primaries smpte170m -color_trc bt709 -vcodec libx264 -brand mp42 -c:v libx264 -profile:v baseline drop.mp4

得到以下信息：

$ mediainfo drop.mp4 
General
Complete name                            : drop.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (isom/iso2/avc1/mp41)
File size                                : 1.82 MiB
Duration                                 : 6 s 67 ms
Overall bit rate                         : 2 511 kb/s
Writing application                      : Lavf58.20.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L3.1
Format settings                          : 3 Ref Frames
Format settings, CABAC                   : No
Format settings, ReFrames                : 3 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 6 s 67 ms
Bit rate                                 : 2 509 kb/s
Width                                    : 960 pixels
Height                                   : 540 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 30.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.161
Stream size                              : 1.81 MiB (100%)
Writing library                          : x264 core 155 r2917 0a84d98
Encoding settings                        : cabac=0 / ref=3 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=23.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Color range                              : Limited
Color primaries                          : BT.601 NTSC
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.470 System B/G
Codec configuration box                  : avcC

但当我试着玩这个游戏时，我会发现一个错误：

$ gst-launch-1.0 playbin uri=file:///home/mendel/coral/google-coral/example-object-tracker/gstreamer/drop.mp4
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Got context from element 'sink': gst.gl.GLDisplay=context, gst.gl.GLDisplay=(GstGLDisplay)"\(GstGLDisplayWayland\)\ gldisplaywayland0";
Got context from element 'playsink': gst.gl.GLDisplay=context, gst.gl.GLDisplay=(GstGLDisplay)"\(GstGLDisplayWayland\)\ gldisplaywayland0";
WARNING: from element /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0/GstCapsFilter:capsfilter0: not negotiated
Additional debug info:
gstbasetransform.c(1415): gst_base_transform_reconfigure (): /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0/GstCapsFilter:capsfilter0:
not negotiated
ERROR: from element /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0/GstQTDemux:qtdemux0: Internal data stream error.
Additional debug info:
qtdemux.c(6073): gst_qtdemux_loop (): /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0/GstQTDemux:qtdemux0:
streaming stopped, reason not-negotiated (-4)
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
Freeing pipeline ...

我做错了什么？

编辑：

以下工作：

gst-launch-1.0 filesrc location=drop.mp4 ! decodebin ! autovideoconvert ! autovideosink

但这不是

$ gst-launch-1.0 filesrc location=drop.mp4 ! decodebin ! videoconvert ! autovideosink
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Got context from element 'autovideosink0': gst.gl.GLDisplay=context, gst.gl.GLDisplay=(GstGLDisplay)"\(GstGLDisplayWayland\)\ gldisplaywayland0";
WARNING: from element /GstPipeline:pipeline0/GstDecodeBin:decodebin0: Delayed linking failed.
Additional debug info:
./grammar.y(510): gst_parse_no_more_pads (): /GstPipeline:pipeline0/GstDecodeBin:decodebin0:
failed delayed linking some pad of GstDecodeBin named decodebin0 to some pad of GstVideoConvert named videoconvert0
ERROR: from element /GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstQTDemux:qtdemux0: Internal data stream error.
Additional debug info:
qtdemux.c(6073): gst_qtdemux_loop (): /GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstQTDemux:qtdemux0:
streaming stopped, reason not-linked (-1)
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
Freeing pipeline ...

我还是很困惑-我是不是错过了一些最基本的东西？

Answer 1

你写你在使用谷歌开发板。假设这是一些嵌入式开发板，则该板上的解码器很有可能是用硬件实现的。因此，最有可能的情况是，解码后的最终图像缓冲区驻留在GPU内存中。

autovideoconvert可能会选择一个在这些GPU缓冲器上工作的颜色转换器(opengl？维亚皮？这是你会发现的)。另一方面，videoconvert对主机主内存中的缓冲区进行操作。因此，在您使用之前，您需要将视频缓冲区下载到主机内存--例如，在使用gldownload缓冲区的情况下。