Alexander Leidinger

Just another weblog

Dec
13

Sam­sung HMX-H200 camcorder

My wife decided that we need a cam­corder. As I am a good hus­band, I do not com­plain (she pays :-D ).

There was an offer in a super mar­ket nearby. Not as low as you can find in the inter­net, but if there is a prob­lem, it is much more easy to com­plain. For some­thing like this, I/we pre­fer this and am-are OK to spend a lit­tle bit more money for this con­ve­nience.

This cam­corder is record­ing to SDHC cards. Such cards have a speed rat­ing, and you need to take some min–speed one, to be able to record videos with a cam­corder. Unfor­tu­nately Sam­sung does not list the speed rat­ing some­where. I searched on the Sam­sung site in the spec­i­fi­ca­tions and in the FAQ. Noth­ing. After a lit­tle bit of googling I at least found a review where the record­ing time for spe­cific card-sizes where listed.

So I took the card-size in MB, divided it by the record­ing time in sec­onds, and got the data trans­fer rate per sec­ond for the spec­i­fied res­o­lu­tions. The 1080i res­o­lu­tion has the high­est trans­fer rate and as such it is the most inter­est­ing one to decide what kind of card one needs.

The high­est trans­fer rate seems to be less than 2.2 MB/s, so a class 4 SDHC card should be enough.

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Dec
07

Sony Bravia and HD videos (via DLNA)

I made some more tests which video res­o­lu­tions my TV accepts via DLNA. While I was look­ing before a SD res­o­lu­tions, this time I took care about some HD res­o­lu­tions.

As the Sin­tel video in the 1024×436 res­o­lu­tion did not play, I tried to reen­code it to 1024×720 (for the enabled x264 options see below). This did not work either. After that I went to the offi­cial res­o­lu­tion of 1280×720, and this works. Ini­tially this video was encoded as High@L3.1, but with this the TV pro­duced some arti­facts on play­back. After chang­ing this to High@L4.0 (sim­ply by remux­ing instead of reen­cod­ing), the play­back was fine (warn­ing: increas­ing the H.264 level is OK, decreas­ing it if the video does not com­ply to the low­ered level, may cause prob­lems). I miss a set­ting in avide­mux for the level, it would be nice if there would be the pos­si­bil­ity to set it.

I also tested if the 1280×544 ver­sion of the Sin­tel video plays fine on the TV or not. It does not play fine, so there is prob­a­bly a hard require­ment on the com­plete res­o­lu­tion for HD video.

While doing this I noticed that tsMuxeR is trun­cat­ing the audio, instead of the 6 chan­nel audio it was before, the remuxed file has only two channels.

As I did not want to always go through all the set­tings to enter what I want, I made a lit­tle avidemux-script to setup (ECMA script + xml) every­thing for me. This was easy, I just took an exist­ing one (the Sony PSP one) as a base and changed the encod­ing options and the tar­get con­tainer (unluck­ily avide­mux 2.5.4 does not sup­port H.264 in MPEG-TS yet, so I have to use a MP4 con­tainer and remux it into the MPEG-TS stream afterwards).

The options I used for the x264-reencoding are –8x8dct –analyse all –mixed-refs –bime –weightb –subme 9 –b-rdo –ref 4 –b-adapt 2 –bframes 4 –direct auto –me umh (this includes b-pyramid, for which there are reports that it does not work).

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Dec
03

Stream­ing video to a Sony Bravia (via DLNA)

I have a Sony Bravia TV with a net­work (eth­er­net) con­nec­tion. Let­ting aside the fact that he is in another sub­net than my NAS and as such I can not use a DLNA (UPnP-AV) server (it is using mul­ti­cast and the Sim­ple Ser­vice Dis­cov­ery Pro­to­col (SSDP) which is not tra­vers­ing sub­nets in the WLAN-LAN-ADSL-router I use), there is no good expla­na­tion from Sony what I can feed to the TV.

When search­ing the net I can find some obscure sug­ges­tions and descrip­tions, but not all of them work for all peo­ple which try them. So it seems I have to research this myself. Luck­ily my router has a build-in UPnP-AV server which I can use to play around (the file size is lim­ited to the size of the USB mem­ory stick I have con­nected to the router, as he can not stream con­tent which is avail­able in a NAS in the network).

Sony tells the TV is able to receive MPEG2 TS and PS con­tain­ers. MPEG2 PS is more or less what you have on DVD. It is able to play SD and HD con­tent from the PS con­tainer, and the video for­mat needs to be MPEG2. They do not explain what SD or HD means in this con­text (the valid res­o­lu­tions), and they do not tell what kind of audio is allowed.

For the MPEG2 TS con­tainer they addi­tion­ally allow H.264 video, and they spec­ify EU, EU-T and EU-ISO as sup­ported in this case. Again, they do not explain what those EU* parts are sup­posed to mean.

For the unspec­i­fied audio I assume this means AC-3, AAC and MPEG Audio Layer 2 (some peo­ple use MP2 to describe this audio for­mat). I suc­cess­fully tested AAC and AC-3, and I have read that MP2 works too. Based upon my expe­ri­ences with the video part (more below) I assume the sam­pling rate and bitwidth mat­ter. So far I tried with 48 kHz and 16 bit per channel.

For the EU* parts I have not found any trust­wor­thy ref­er­ence what this could mean, but it looks this refers to some aspects of DVB/DVB-T/DVB-S(2) as it is used in Europe. I guess this is a bit linked with valid res­o­lu­tions the TV is able to handle.

For the video part I have found mixed reports. From hat I have read in the Wikipedia page of the H.264 video for­mat, I assumed the fail­ures are related to a wrong res­o­lu­tion and maybe the fact that some parts of the video do not con­form to spe­cific “lev­els” of the H.264 for­mat. Some tell you are not allowed to use more than X ref­er­ence frames, some tell you can not use advanced fea­ture Y.

The first test I did was to take the Sin­tel video from Blender. I down­loaded the MP4 ver­sion and remuxed it into a MPEG2-TS con­tainer (I used tsMuxeR to do this). The TV was able to play the AAC audio, but it did not show the video. When I look at the video prop­er­ties, I see that it has a res­o­lu­tion of 1280×544 at 24 FPS. For H.264 videos which use the “High” pro­file and are com­pat­i­ble up to level 4.1, I do not see this res­o­lu­tion listed as valid in the Wikipedia page. Valid res­o­lu­tions are 1280×720 at 30, 60 and 68.3 FPS, and 1280×1024 at 42.2 FPS. This could explain why it is not working.

As a sec­ond test I took a video resized it to 624×256 (I did not pay much atten­tion to the scale in the pro­gram I used to test this, I just hoped it takes a good one, now that I try to sum­ma­rize what I inves­ti­gated so far, I see that this size is not one of the valid sizes listed in the lev­els for H.264) at 23.976 FPS and reen­coded it with the default options of the x264 encoder. The result­ing video played just fine on the TV.

My third test was to encode a resized (from 640×272 to 640×480) video at 23.976 FPS with weighted, upto 4 adap­tive B-frames, mixed ref­er­ences, 4 ref­er­ence frames, and some other options (this includes B-pyramid, which seems to be enabled by default). And again, the result­ing video played just fine (despite the fact that I found com­ments in the net which sug­gest that B-pyramid needs to be disabled…).

I still have to test some HD sizes, but it looks like one key aspect for com­pat­i­bil­ity is that the video is encoded with the right res­o­lu­tion (I have to admit, I do not really know what this means, as one video had a res­o­lu­tion which was dif­fer­ent from what the valid sizes for the H.264 lev­els are) and com­plies to only level 4.1 (or 4) and below (basi­cally this means to obey some bitrate lim­i­ta­tions and the num­ber of max. ref­er­ence frames for the given res­o­lu­tion). The 23.976 FPS I men­tioned above are not listed as one of the valid FPS in the lev­els for H.264, so I do not think the FPS have to strictly con­form to what is spec­i­fied for the lev­els. It looks more this is just an upper limit so that the video could also use some lower FPS.

So far I took the sin­tel video and added some black bor­ders on top and below to get to the 1080×720 res­o­lu­tion. I used avide­mux 2.5.4 for this. The ver­sion I tried can only pro­duce a MP4 con­tainer with this video/audio com­bi­na­tion, and my hope was to remux it with tsMuxeR to a MPEG2-TS, but tsMuxeR does not find a valid video or audio stream inside the MP4 con­tainer. I am still search­ing for a pro­gram which is able to remux the result­ing MP4 into a MPEG2-TS. I found a tool which extracts the streams from the MP4 con­tainer, but the only free MPEG2-TS muxer seems to be tsMuxeR, which I was not able to con­vince to mux the two streams into a MPEG2-TS file. It seems I have either to wait until avide­mux knows how to gen­er­ate MPEG2-TS streams with H.264 and AAC, or until it gen­er­ates a MP4 con­tainer with H.264 and AAC which tsMuxeR is able to handle.

What I also want to test is, if I can use the open-gop options (either in “nor­mal” or in “blu­ray” mode), but I did not took the time to test this.

The only think I can tell defin­i­tively ATM is, that despite to all the infor­ma­tion I found in the net about this, noth­ing can be told about the hard require­ments except, that the video encod­ing can not exceed level 4.1 (or 4), because so far no hard­ware decoder chip seems to sup­port a higher level. It seems I can use more or less all options avail­able for the H.264 encod­ing, and the res­o­lu­tion and FPS does not seem to mat­ter that much. I looks more that you have to find a ver­sion of an H.264 encoder which works for you, and after that you can more or less do what you want.

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